Hyponymy

This relation is important for describing nouns, but it also figures in the description of verbs and, to a lesser extent, adjectives. It is concerned with the labelling of sub-categories of a word’s denotation: what kinds of Xs are there and what different kinds of entities count as Ys. For example, a house is one kind of building, and a factory and a church are other kinds of building; buildings are one kind of structure; dams are another kind of structure.

The pattern of entailment that defines hyponymy is illustrated in (3.8).

If it is true that there is a house next to the gate, then (with respect to the same gate at the same point in history) it must be true that there is a building next to the gate; it cannot be otherwise. On the other hand, if we are given (3.8b) as true information, then we cannot be sure that (3.8a) is true. It might be true, but there are other possibilities: the building next to the gate could be a barn or any other kind of building. That is why the second half of (3.8c) has been scored out; to show that – though it could follow – (3.8a) does not have to follow from (3.8b). Terminology: building is a superordinate2 for house and nouns labelling other kinds of building. House, barn, church, factory, hangar and so forth are hyponyms of building.

It is possible to generalize about the pattern shown in (3.8): a sentence, such as (3.8a), containing a hyponym of a given superordinate entails a sentence that differs from the original one only in that the superordinate has been substituted for its hyponym, as in (3.8b). The sentence with the hyponym entails the corresponding sentence with the superordinate replacing it, but the entailment goes one way only – not from the sentence containing the superordinate. This generalization is not watertight. There are some other conditions that would have to be stated, for instance the sentences must not be negative. With reference back to (3.8), if we knew that it was true that there isn’t a building next to the gate, then we could be sure that (talking about the same gate at the same time) there isn’t a house next to the gate. Because of the negative, n’t, the entailment goes the other way round: from the sentence with the superodinate to the corresponding one with the hyponym. Incidentally, this highlights the fact that there being a building by the gate is a necessary condition for there to be a house by the gate. If there is no building at the gate, then there cannot be a house there. Intuitively it is reasonable to say that ‘building’ is a component of the meaning of house: a house is a ‘building for living in’

Prototypicality has to be brought into consideration for the has relation, but is not needed for hyponymy.