Trivia glossary: 220 terms explained, from archipelago to Zelda

Glossary

220 words from the game, the ocean you dive through and the trivia prompts, each explained in a sentence or two.

The game

Iceberg chart: A popular internet format that draws a subject as an iceberg. Facts everybody knows float on the visible tip; the more obscure a fact is, the further down the iceberg it sits. Icillion turns the format into a game: your answers are placed on the iceberg by how rare they are.
The Tip: Level 1. The answers almost everybody gives, the ones that float above the water. Worth 10 points.
Below the Surface: Level 2. Solid answers just under the waterline: well known, but not the first thing most people say. Worth 25 points.
The Deep: Level 3. Answers that not many people get down to. Worth 50 points.
The Abyss: Level 4. Answers very few people know. Worth 85 points.
Below the Iceberg: Level 5, the bottom. Every prompt has exactly one legendary answer here, worth the full 100 points.
Legendary answer: The single rarest accepted answer to a prompt. Finding it takes you to the maximum depth for that prompt.
Daily iceberg: The seven prompts everyone plays on the same day. A new one starts at midnight UTC.
Free play: Unlimited rounds on all topics or on just one, with your own timer setting. Free play does not change your streak.
Streak: How many daily icebergs in a row you have finished.
Rarity percentile: An estimate of how your score compares with simulated rounds, shown at the end of a round. It is a model, not a statistic of real players.
Dive: Each answer sends the submarine down. Rare answers dive further; a perfect round reaches the deepest point of the ocean.
Trivia: Small facts about a wide range of subjects, and the quiz games built on knowing them. In open trivia like Icillion, a prompt has many right answers instead of one.

The ocean

Sunlight zone: The top layer of the ocean, roughly the first 200 metres, where sunlight is strong enough for plants and algae to grow. Also called the epipelagic zone.
Twilight zone: From about 200 to 1,000 metres down. A little light still reaches it, but not enough for photosynthesis. Also called the mesopelagic zone.
Midnight zone: From about 1,000 to 4,000 metres. No sunlight reaches it; the only light comes from animals that glow. Also called the bathypelagic zone.
Abyssal zone: The cold, dark water from about 4,000 to 6,000 metres, above the vast abyssal plains of the sea floor.
Hadal zone: The deepest part of the ocean, below about 6,000 metres, found almost only in ocean trenches. Named after Hades.
Challenger Deep: The deepest known point in the ocean, in the Mariana Trench in the western Pacific, close to 11,000 metres down. The bottom of every Icillion dive.
Mariana Trench: A crescent-shaped trench in the western Pacific Ocean, east of the Mariana Islands. It holds the deepest known point on Earth, the Challenger Deep.
Bioluminescence: Light made by living things through a chemical reaction. Anglerfish, many jellyfish and some squid use it to hunt, hide or signal.
Marine snow: A slow, constant fall of tiny particles, mostly bits of dead plankton, from the upper ocean to the deep. It feeds much of the life below.
Iceberg: A large piece of freshwater ice that has broken off a glacier or an ice shelf and floats in open water. Only about a tenth of it shows above the surface.
Marine invertebrate: A sea animal without a backbone, such as a jellyfish, an octopus, a crab, a starfish or a sea urchin.

Geography

Archipelago: A group or chain of islands, such as the Philippines, the Faroe Islands or Fiji.
Island: A piece of land smaller than a continent that is completely surrounded by water.
Peninsula: A piece of land surrounded by water on most sides but joined to the mainland, such as Italy, Iberia or Florida.
Continent: One of the Earth’s very large land masses: Africa, Antarctica, Asia, Europe, North America, Oceania (or Australia) and South America.
Sovereign state: A country with its own government that is independent of any other; a territory or a region of another country is not.
Landlocked country: A country with no coastline on the open sea, such as Switzerland, Bolivia or Mongolia.
Microstate: A sovereign state with a very small area or population, such as Monaco, San Marino, Liechtenstein or Nauru.
Capital city: The city where a country’s government sits. It is not always the largest city: think of Canberra, Ottawa or Bern.
Oceania: The region made of Australia, New Zealand, New Guinea and the island groups of Melanesia, Micronesia and Polynesia in the Pacific.
US state: One of the fifty constituent states of the United States of America, each with its own government, such as Texas, Vermont or Hawaii.
River: A natural stream of fresh water that flows towards an ocean, a sea, a lake or another river.
Lake: A large body of water surrounded by land. Most hold fresh water; some, like the Caspian Sea, are salty.
Sea: A large body of salt water, usually part of an ocean and partly enclosed by land, such as the Mediterranean or the Baltic.
Strait: A narrow channel of water that connects two larger seas, such as the Strait of Gibraltar or the Bosporus.
Bay and gulf: A part of the sea that cuts into the land. A gulf is usually larger and more enclosed than a bay: the Bay of Biscay, the Gulf of Mexico.
Canal: A waterway dug by people for ships or for water supply, such as the Suez Canal or the Panama Canal.
Mountain range: A chain of mountains formed together, such as the Andes, the Alps or the Carpathians.
Volcano: An opening in the Earth’s crust where molten rock, ash and gases escape, usually building a mountain over time.
Waterfall: A place where a river or stream drops over a vertical edge, such as Angel Falls, Niagara Falls or Victoria Falls.
Desert: An area that gets very little rain. Deserts can be hot, like the Sahara, or cold, like the Gobi and Antarctica.
National park: An area protected by a government for its nature, landscape or wildlife, such as Yellowstone or the Plitvice Lakes.
Tectonic plate: One of the huge slabs of rock that make up the Earth’s outer shell. Their slow movements cause earthquakes, volcanoes and mountain ranges.
Equator: The imaginary line around the middle of the Earth, halfway between the poles, at 0° latitude.

Nature

Mammal: A warm-blooded animal with hair or fur that feeds its young on milk, from mice and bats to whales and humans.
Bird: A warm-blooded animal with feathers, a beak and wings that lays hard-shelled eggs. Not all birds fly: think of penguins and ostriches.
Bird of prey: A bird that hunts other animals with sharp talons and a hooked beak, such as eagles, hawks, falcons and owls. Also called a raptor.
Reptile: A cold-blooded animal with scales that usually lays eggs on land, such as snakes, lizards, turtles and crocodiles.
Amphibian: A cold-blooded animal that usually starts life in water and later lives on land, such as frogs, toads, newts and salamanders.
Frog and toad: Both are tailless amphibians. Toads are usually drier, wartier and more at home on land; but the difference is not a strict scientific one.
Insect: A small animal with six legs and a body in three parts (head, thorax, abdomen), such as ants, beetles, bees and butterflies.
Arachnid: An animal with eight legs and no antennae, such as spiders, scorpions, ticks and mites.
Crustacean: An animal with a hard outer shell and jointed legs that mostly lives in water, such as crabs, lobsters, shrimp and krill.
Fish: A cold-blooded animal that lives in water, breathes with gills and usually has fins and scales.
Shark: A fish with a skeleton of cartilage instead of bone, rows of replaceable teeth and gill slits on its sides.
Cetacean: A whale, dolphin or porpoise: a mammal that lives its whole life in water and breathes air through a blowhole.
Marsupial: A mammal whose young finish developing in a pouch, such as the kangaroo, the koala or the opossum.
Primate: The group of mammals that includes lemurs, monkeys, apes and humans.
Rodent: A mammal with large front teeth that keep growing, such as mice, rats, squirrels, beavers and capybaras.
Antelope: A fast, slender grazing animal with horns, mostly from Africa and Asia, such as the gazelle, the impala or the springbok.
Breed: A group of domestic animals with a shared look and ancestry, shaped by people through selective breeding, such as the beagle or the Maine Coon.
Dinosaur: A group of reptiles that ruled the land for over 160 million years. Birds are the only dinosaurs alive today.
Extinct: No longer living anywhere. The dodo, the woolly mammoth and the thylacine are extinct.
Penguin: A flightless seabird of the Southern Hemisphere that swims with its flippers. Emperor penguins can dive deeper than 500 metres.
Conifer: A tree or shrub that carries its seeds in cones, usually with needles, such as pines, firs, spruces and cedars.
Succulent: A plant that stores water in thick leaves, stems or roots, such as aloe, agave and every cactus.
Flowering plant: A plant that makes flowers and seeds inside fruit. Most plants on Earth, from grasses to oak trees, are flowering plants.
Fungus: A living thing that is neither plant nor animal, such as mushrooms, moulds and yeasts. It feeds by breaking down other matter.
Biome: A large natural area with a typical climate, plants and animals, such as a tundra, a desert or a rainforest.
Pollinator: An animal that carries pollen from flower to flower, such as bees, butterflies, hummingbirds and some bats.

Food

Herb and spice: Herbs are the leaves of plants used for flavour, such as basil; spices come from seeds, bark, roots or fruit, such as pepper or cinnamon.
Cheese: A food made by curdling milk and pressing, salting and often ageing the curds. There are well over a thousand kinds.
Pasta and noodles: Dough of grain and water, often with egg, cut into shapes and cooked in water. Pasta is the Italian family; noodles are found all over Asia.
Dumpling: A piece of dough, often filled, that is boiled, steamed or fried. Nearly every cuisine has its own.
Pastry: A dough of flour, fat and water that bakes into a flaky or crumbly shell, and the sweet or savoury bakes made from it.
Dessert: A sweet course eaten at the end of a meal, such as cake, ice cream or crème brûlée.
Citrus: The family of fruit that includes oranges, lemons, limes, grapefruit and mandarins.
Nut: In the kitchen, any hard-shelled seed or dry fruit with an edible kernel. Botanically, peanuts are legumes and almonds are seeds of a drupe.
Pseudocereal: A plant whose seeds are eaten like grain but which is not a grass, such as quinoa, buckwheat or amaranth.
Fermentation: A process in which microbes such as yeast and bacteria change food, as in bread, yoghurt, kimchi or wine.
Herbal infusion: A drink made by steeping herbs, flowers or fruit in hot water, such as chamomile or rooibos. Strictly, tea comes only from the tea plant.
Espresso: Strong coffee made by forcing hot water through finely ground beans under pressure. It is the base of the cappuccino, the latte and the flat white.
Cocktail: A mixed drink, usually of a spirit with juice, syrup, bitters or other flavours, such as the mojito or the negroni.
Sauce: A liquid or creamy mixture served with food to add flavour or moisture, such as béchamel, pesto or soy sauce.
Cuisine: The style of cooking of a country or region, with its own ingredients, dishes and habits.
Flatbread: Bread rolled thin and often made with little or no yeast, such as naan, pita, tortilla and lavash.

Science

Chemical element: A pure substance made of one kind of atom, defined by the number of protons in its nucleus. There are 118 known elements.
Solar System: The Sun and everything held by its gravity: eight planets, their moons, dwarf planets, asteroids and comets.
Moon: A natural satellite: a body that orbits a planet. Jupiter and Saturn each have dozens, from Ganymede and Titan to tiny captured rocks.
Star: A huge ball of hot gas that shines by nuclear fusion in its core. The Sun is the nearest; Sirius is the brightest in the night sky.
Constellation: One of the 88 officially recognised areas of the night sky, each named after a pattern of stars such as Orion or Cassiopeia.
Galaxy: A huge system of stars, gas and dust held together by gravity. Our own is the Milky Way.
Nebula: A cloud of gas and dust in space, either where new stars are forming or left behind when a star dies.
Comet: A small icy body that grows a glowing head and tail when its orbit brings it close to the Sun.
Space telescope: A telescope placed in orbit, above the blur of the atmosphere, such as Hubble or the James Webb Space Telescope.
Particle: In physics, one of the tiny building blocks of matter and forces, such as the electron, the quark or the photon.
Law of physics: A short statement, often an equation, of how nature always behaves under given conditions, such as Newton’s laws or Ohm’s law.
Energy: The ability to do work or cause change. It takes many forms (kinetic, thermal, chemical, nuclear) and changes from one to another.
Unit of measurement: A fixed amount used to measure a quantity. The SI system has seven base units, among them the metre, the kilogram and the second.
Bone: One of the hard parts of the skeleton. An adult human has 206, from the femur to the tiny stapes in the ear.
Organ: A part of the body made of several tissues that does a particular job, such as the heart, the liver or the skin.
Muscle: Tissue that contracts to move the body or its organs. Humans have about 600 skeletal muscles.
Hormone: A chemical messenger made by a gland and carried in the blood, such as insulin, adrenaline or melatonin.
Organelle: A small structure inside a cell with its own job, such as the nucleus, the mitochondria or the ribosomes.
Disease: A disorder of the body or mind with recognisable signs, caused by infection, genes, environment or way of life.
Gemstone: A mineral, rock or organic material cut and polished for jewellery, such as diamond, emerald, opal or amber.
Rock type: Rocks form in three ways: igneous from cooled magma (granite), sedimentary from layers of sediment (sandstone), and metamorphic from heat and pressure (marble).
Cloud type: Clouds are named by shape and height: cumulus (heaps), stratus (layers), cirrus (wisps) and combinations like cumulonimbus.
Theorem: A mathematical statement that has been proved from earlier results, such as Pythagoras’ theorem.
Geometric shape: A figure defined by its outline, such as a triangle, a hexagon or a circle; in three dimensions, a cube or a sphere.
Scientific instrument: A device used to observe or measure, such as a thermometer, a microscope or a seismometer.
Branch of science: One field of scientific study, such as physics, biology, geology or astronomy, each with many smaller branches.

Chemistry

Acid: A substance that gives away hydrogen ions (protons) in water and has a pH below 7, such as hydrochloric acid or citric acid.
Base: A substance that accepts hydrogen ions or releases hydroxide ions, with a pH above 7, such as sodium hydroxide or ammonia.
pH: A scale from 0 to 14 for how acidic or basic a solution is. 7 is neutral, lower is acidic, higher is basic.
Chemical indicator: A substance that changes colour when a solution changes, most often its acidity. Litmus and phenolphthalein are the classic examples.
Chemical compound: A substance made of two or more elements bonded in a fixed ratio, such as water (H₂O) or table salt (NaCl).
Polymer: A large molecule made of many repeating smaller units. Plastics such as polyethylene, and natural ones such as cellulose and DNA, are polymers.
Alloy: A mixture of a metal with other elements, made to be stronger or more useful. Steel, brass and bronze are alloys.
Metal: An element that is usually shiny, conducts heat and electricity and can be bent or drawn into wire, such as iron, copper and gold.
Functional group: A specific group of atoms inside a molecule that gives it typical reactions, such as the hydroxyl group of alcohols or the carboxyl group of acids.
Periodic table: The chart of all chemical elements, arranged by atomic number in rows (periods) and columns (groups) with similar properties.
Halogen: An element of periodic-table group 17: fluorine, chlorine, bromine, iodine, astatine and tennessine. They react readily to form salts.
Noble gas: An element of group 18: helium, neon, argon, krypton, xenon, radon and oganesson. They barely react with anything.
Lanthanide: One of the fifteen metals from lanthanum to lutetium, often called rare earths. They are used in magnets, screens and lasers.
Actinide: One of the fifteen radioactive metals from actinium to lawrencium, including uranium and plutonium.
Hydrocarbon: A compound made only of carbon and hydrogen, such as methane, propane or benzene.
Alcohol (chemistry): An organic compound with a hydroxyl (–OH) group, such as methanol, ethanol or glycerol.
Sugar: A sweet, soluble carbohydrate such as glucose, fructose or sucrose. Sugar alcohols like xylitol are related but not sugars.
Amino acid: One of the small molecules that join in chains to make proteins. The body uses twenty standard ones, such as glycine and leucine.
Fatty acid: A long chain of carbon atoms ending in an acid group, the building block of fats and oils, such as oleic or palmitic acid.
Mineral: A naturally occurring solid with a set chemical makeup and an ordered crystal structure, such as quartz, feldspar or calcite.
Salt: In chemistry, any compound made of positive and negative ions, formed when an acid reacts with a base. Table salt is just one of them.
Solvent: A substance, usually a liquid, that dissolves other substances. Water is the most common; acetone and ethanol are others.
Chemical reaction: A process in which substances change into new ones by breaking and forming bonds, such as combustion or neutralisation.
Named reaction: A chemical reaction known by the name of the chemist who found it, such as the Diels–Alder reaction or the Grignard reaction.
Chemical bond: The force that holds atoms together in molecules and crystals: covalent, ionic and metallic bonds are the main kinds.
Chromatography: A family of techniques that separate a mixture by letting it travel through a material at which its parts move at different speeds.
Laboratory glassware: The glass equipment of a chemistry lab, such as beakers, flasks, burettes, pipettes and condensers.

Computer science

Algorithm: A precise list of steps for solving a problem, such as sorting a list or finding the shortest route.
Sorting algorithm: An algorithm that puts items in order, such as quicksort, merge sort or bubble sort. They differ in speed and memory use.
Graph algorithm: An algorithm that works on networks of nodes and edges, such as Dijkstra’s shortest path or breadth-first search.
Search algorithm: An algorithm that finds an item or a path, such as binary search or A*.
Data structure: A way of organising data in a program so it can be used efficiently, such as an array, a linked list, a hash table or a tree.
Operating system: The software that runs a computer and lets programs use its hardware, such as Windows, macOS, Linux or Android.
Linux distribution: An operating system built from the Linux kernel plus a chosen set of software, such as Ubuntu, Debian, Fedora or Arch.
Unix command: A small program run from a Unix or Linux shell, such as ls, grep or chmod.
Protocol: An agreed set of rules for how computers exchange data, such as HTTP, TCP or DNS.
HTTP method: The verb of a web request that says what to do with a resource: GET, POST, PUT, PATCH, DELETE and a few more.
Network topology: The layout of a network’s connections, such as star, ring, bus or mesh.
Database: An organised store of data that a program can query and update, such as PostgreSQL, MySQL or SQLite.
SQL: Structured Query Language, the standard language for asking relational databases for data, with keywords like SELECT, JOIN and WHERE.
File format: A standard way of encoding information in a file, such as PNG for images, MP3 for audio or PDF for documents.
Data compression: Encoding data in fewer bits. Lossless formats like ZIP keep every bit; lossy ones like JPEG drop detail people won’t notice.
Instruction set architecture: The set of machine instructions a processor understands, such as x86, ARM or RISC-V.
Logic gate: A tiny circuit that computes a simple logical function of its inputs, such as AND, OR, NOT or XOR.
CPU scheduling: How an operating system decides which program runs next on the processor, such as round robin or shortest job first.
Design pattern: A reusable, named solution to a common problem in software design, such as the singleton or the observer.
Programming paradigm: A style of programming, such as object-oriented, functional or logic programming.
Programming language: A formal language for writing instructions a computer can run, such as Python, C or JavaScript.
Markup language: A language that annotates text with structure or formatting, such as HTML, Markdown or LaTeX.
Integrated development environment: An application that bundles a code editor, a debugger and build tools, such as Visual Studio or IntelliJ IDEA.
Version control: A system that records changes to files over time so you can go back to earlier versions, such as Git.
Package manager: A tool that installs and updates software libraries and their dependencies, such as npm, pip or apt.
Software framework: A reusable base of code that gives an application its structure, such as Django for Python or React for user interfaces.
Hash function: A function that turns data of any size into a fixed-size value. Used in hash tables, checksums and cryptography; SHA-256 is one.
Encryption: Turning readable data into a code that only someone with the right key can read, with ciphers such as AES or RSA.
Character encoding: A rule for turning text characters into numbers a computer can store, such as ASCII or UTF-8.
Software license: The legal terms for using and sharing software, such as the MIT License or the GNU GPL.
Web browser: An application for viewing web pages, such as Chrome, Firefox or Safari.

History

Dynasty: A line of rulers from the same family, such as the Tudors, the Ming or the Ptolemies.
Emperor: The ruler of an empire, often above kings, such as Augustus in Rome or Napoleon in France.
Monarch: A king, queen or other ruler who holds power for life and usually inherits it.
Pharaoh: The title of the rulers of ancient Egypt, such as Tutankhamun or Ramesses II.
Sultan: The title of rulers in many Muslim states, above all the Ottoman Empire, such as Suleiman the Magnificent.
Tsar: The title of the rulers of Russia until 1917, such as Ivan the Terrible or Peter the Great.
President: The elected head of a republic. The United States has had more than forty-five since George Washington.
Empire: A large state that rules over many peoples and territories, such as the Roman, Mongol or British Empire.
Ancient civilisation: A complex early society with cities, writing and government, such as Mesopotamia, ancient Egypt or the Indus Valley.
Explorer: A person who travels into regions unknown to their own people, such as Marco Polo, Ibn Battuta or Roald Amundsen.
Battle: A fight between armed forces at one place and time, such as Hastings, Waterloo or Stalingrad.
Treaty: A formal written agreement between states, such as the Treaty of Westphalia or the Treaty of Versailles.
Archaeological site: A place where traces of past human life have been found and studied, such as Pompeii or Göbekli Tepe.
Trade route: A path used over a long time to carry goods between regions, such as the Silk Road or the Amber Road.
Writing system: A set of signs used to write a language, such as the Latin alphabet, Chinese characters or cuneiform.
Philosopher: A thinker who studies basic questions about knowledge, existence, ethics and reason, such as Socrates, Confucius or Kant.

Culture

Language: A system of words and grammar people use to communicate. About 7,000 are spoken today.
Musical instrument: An object made or used to produce music, grouped as strings, woodwind, brass, percussion and keyboards.
Olympic sport: A sport that is or has been part of the Olympic Games, such as athletics, fencing or, once, tug of war.
Board game: A game played by moving pieces on a board, from chess and Go to modern games like Catan.
Card game: A game played with a deck of cards, such as poker, bridge or solitaire.
Currency: The money used in a country, such as the euro, the yen or the Romanian leu.
Mythology: The traditional stories of a culture about its gods, heroes and the origin of the world.
Mythical creature: An animal or being from legend, such as the dragon, the phoenix or the kraken.
Superhero: A fictional hero with extraordinary powers who fights crime or evil, such as Superman or Spider-Man.
Art movement: A style shared by a group of artists during a period, such as Impressionism, Cubism or Surrealism.
Architectural style: A recognisable way of designing buildings, such as Gothic, Baroque or Brutalism.
Classical music: Art music of the Western tradition, especially from about 1750 to 1820, and more widely all of it, from Bach to Stravinsky.
Opera: A drama set to music in which the story is sung, such as Carmen or La traviata.
Ballet: A form of theatrical dance with precise, formal steps, such as Swan Lake or The Nutcracker.
Musical: A stage show that tells a story through songs, spoken dialogue and dance, such as Les Misérables or Hamilton.
Music genre: A category of music with shared style and roots, such as jazz, reggae, techno or fado.
Dance style: A particular kind of dance with its own steps and music, such as the tango, the waltz or the hora.
Martial art: A system of combat practised as a sport, for self-defence or as a discipline, such as judo, karate or capoeira.
Poetry: Writing that uses rhythm, sound and imagery, often in lines and verses. Its writers are poets, such as Homer, Rumi or Eminescu.
Novel: A long work of fiction in prose. Its writers are novelists, such as Jane Austen, Dostoevsky or Toni Morrison.
Sculpture: Art made in three dimensions by carving, modelling or casting, such as Michelangelo’s David. Its makers are sculptors.
Textile: A fabric made by weaving, knitting or felting fibres, such as cotton, silk, denim or tweed.
Colour: The way light of different wavelengths looks to the eye. Painters and printers name thousands of shades.

Screen

Franchise: A series of films, games or shows set in the same world, such as Star Wars or The Legend of Zelda.
Video game: A game played on a screen, from arcade cabinets and consoles to phones and computers.
Pokémon: The creatures of the Pokémon games and anime, which players catch, train and battle. There are over a thousand.
Animation studio: A company that makes animated films, such as Pixar, Disney Animation or Studio Ghibli.
Film director: The person who leads the making of a film and shapes how it looks and feels, such as Akira Kurosawa or Greta Gerwig.
Fighting game: A video game in which characters fight each other one on one, such as Street Fighter or Mortal Kombat.
Mob: In video games, and Minecraft in particular, any creature that moves on its own, friendly or hostile.
Sandbox game: A video game that lets players build and explore freely rather than follow a fixed story, such as Minecraft.

How deep does your knowledge go?

Seven prompts a day, twenty seconds each. Obvious answers float on the tip of the iceberg; rare ones sink all the way to the trench.

▼ Start today’s iceberg ▼