In grammar, a modifier or qualifier is a word that modifies another word, a phrase, or a clause. In English, there are two kinds of modifiers: adjectives, which modify nouns and pronouns, and adverbs, which modify verbs, adjectives, and other adverbs. A modifier phrase is a phrase that acts as a modifier; English has adjective phrases and adverb phrases. Neither modifiers nor modifier phrases are usually required by a clause's syntax; they are optional, and help modify or limit the extent of the meaning of the word or phrase they modify.

The adjective "green" in "a green tree" modifies and thus limits the meaning of the noun "a tree" in that it cannot be "a deciduous tree in winter", as the adverb "kindly" modifies the past tense of the verb "let" in "she kindly let me borrow her scissors". An adverb may also modify an adjective, such as in "abjectly poor".

Adverbial clauses (or particle phrases) such as "of course", "as it were", etc., commenting on the rest of the sentence or what has gone before in a previous sentence, may also be classed as modifiers, as in "Of course, he was never one to be silent" or "Unfortunately, we arrived late".

Another way of defining a modifier is that it, the adjective or adverb, is more dependent on the part of the sentence it modifies, namely the noun or verb. The noun is independent and may exist on its own, such as "the tree" which then may be modified by "green", or the verb being independent as in "work" in "I work (every day)" may be modified by the adverb "hard" in "I work hard (every day)".

In compound nouns, the first of the two words so combined functions as a modifier, such as "elementary" in "elementary school", "mountain" in "mountain bike", etc.

Lastly, modifiers may be divided into pre-modifier + subject (noun) + post-modifier, as in "land (pre-modifier) mines in wartime (post-modifier)".

See also

• dangling modifier

Grammar | Parts of speech