Modifier noun

In tomato soup, tomato is a modifier noun that modifies the phrasal head soup.

A noun modifier, noun adjunct or attributive noun is a noun that is used as a modifier on another noun.

In English, for example, in the phrase tomato soup, tomato is a noun modifier that modifies the phrasal head soup.

In English, the modifier noun is usually singular, even if that word is usually plural, e.g. trouser in trouser leg. This rule is not always followed however, e.g. sports car, or clothes shop.

We can identify modifier nouns because they:

1. The modifier noun modifies the prototypical meaning of the head noun.
2. The modifier noun is used as a noun generally.
3. They cannot be used in predicative position, unlike adjectives, e.g. *the leg is trouser.

Sometimes ambiguous analysis is possible. For example, in plastic spoon, plastic can be analysed as an adjective (the fork is plastic) or as a modifier noun (the fork is made of plastic). Both analyses are equally valid.

This results in a compound noun, which may be compounded into one word, hyphenated, or spelt as two (or more) words.