Nouns in this dictionary sit in an inheritance hierarchy: each sense has broader terms (the categories it is a kind of) and narrower terms (the kinds of it). A collie is a kind of shepherd dog, which is a kind of working dog, which is a kind of dog, which is a kind of domestic animal, which is a kind of animal. The relation holds between senses, not between spellings — which is where most attempts to follow a chain go wrong.
Two relations, one test
A broader term names the category a sense belongs to. A narrower term names a subtype of it. Lexicographers call them hypernyms and hyponyms; the test for both is the same sentence.
Say “an X is a kind of Y”. If that reads as true, Y is broader than X. A poodle is a kind of dog: true, so dog is broader. A dog is a kind of poodle: false. The relation only runs one way, and that asymmetry is what makes it a hierarchy rather than a web.
It also inherits. If a poodle is a kind of dog and a dog is a kind of animal, a poodle is a kind of animal, without anyone recording that link directly. Everything true of the category is true of everything under it, which is the whole reason the structure is worth having.
Three chains, as recorded
These are read directly off the entries. Each arrow is one recorded broader-term link, and every step in each chain is one you can check by opening the word.
- collie → shepherd dog → working dog → dog → domestic animal → animal
- sparrow → passerine → bird → vertebrate
- espresso → coffee → beverage → food → substance
What the chains show
Read upward and you get a definition. A good dictionary definition is almost always its broader term plus what distinguishes it: a collie is “a silky-coated sheepdog with a long ruff and long narrow head” — a shepherd dog, plus three distinguishing features. Once you see that pattern you see it everywhere, because it is how definitions are built.
Read downward and you get options. “Dog” has narrower terms including puppy, pooch, cur, lapdog, toy dog and hunting dog; “poodle” has toy poodle, miniature poodle, standard poodle and large poodle. If your sentence needs more precision than the word you reached for, the narrower list is where the more precise word already is.
The chains also show how uneven the hierarchy is. Espresso reaches “food” in three steps; sparrow reaches “vertebrate” in three. Dog breeds are recorded in more levels than beverages because the vocabulary is finer-grained, not because dogs are more deeply nested in reality.
The trap: relations connect senses, not spellings
Follow a chain by looking up each broader term as a headword and it will derail. “Dog” records “canine” among its broader terms. Look up canine as a word and its first sense is a tooth — one of the four pointed conical teeth — whose own broader term is “tooth”, then bone, then tissue. Two steps later you are in anatomy and the chain is nonsense.
Nothing is wrong with the data. The link from dog runs to the animal sense of canine, not to the tooth sense. Only the display, which shows a lemma rather than a sense id, invites the wrong jump.
So when you follow a broader term to its page, pick the sense that matches the one you came from. A chain that suddenly changes subject is the signal you took the wrong sense at the last step. It is also the single best demonstration of why a thesaurus organised by word rather than by meaning misleads.
Verbs and adjectives are built differently
The deep hierarchy is a noun phenomenon. There are 117,953 noun entries here and the structure under them runs many levels; there are 21,499 adjective entries and 4,475 adverb entries with almost no hierarchy at all.
Verbs have something related but not identical. “Whisper” is not a kind of “speak” in the way a poodle is a kind of dog — it is a manner of speaking. Lexicographers call these troponyms, and the test sentence changes to “to X is to Y in some particular manner”.
Adjectives are organised as clusters around opposites instead. A head adjective (hot, cold) anchors a group of similar adjectives that have no opposite of their own — which is why our adjective entries show “similar” terms where noun entries show broader and narrower ones. The structure of English is not uniform, and a dictionary that rendered every class the same way would be flattening something real.
Where the hierarchy stops
Climb far enough up any noun chain and you arrive at a small set of top categories — entity, abstraction, physical entity — that have nothing above them. They are marked in the corpus as a distinct file, and they are the roots the whole noun vocabulary hangs from.
They are also useless in a sentence. Nobody has ever needed to call something a physical entity. Their value is structural: they are the point at which two apparently unrelated words turn out to be related, which is what lets a chain answer “what do a collie and an espresso have in common” with a real answer rather than a joke.
Questions
- What is a hypernym?
- The broader category a word belongs to. Dog is a hypernym of poodle; animal is a hypernym of dog. This site labels them “Broader” on each sense, because the relation belongs to the sense rather than to the word.
- What is a hyponym?
- A more specific kind. Poodle, collie and spaniel are hyponyms of dog. They are labelled “Narrower”, and they are the fastest route from a word that is nearly right to the word that is exactly right.
- Why does following a chain of broader terms sometimes go strange?
- Because the link runs between senses and the page shows you a word. “Canine” is broader than “dog” in its animal sense, but the first sense of canine as a headword is a tooth. Choose the matching sense when you follow the link.
- Do verbs and adjectives have broader and narrower terms too?
- Not in the same way. Verbs have troponyms — to whisper is to speak in a manner — and adjectives are grouped into similarity clusters around opposite pairs. The deep inheritance hierarchy is essentially a noun structure.