Real Dictionary

modifier
countable noun: A modifier is a word or group of words that modifies another word or group. In some descriptions of grammar, only words that are used before a noun are called modifiers.

modifier in American English
a person or thing that modifies; esp., a word, phrase, or clause that limits the meaning of another word or phrase
noun: a person or thing that modifies

modifier in British English
noun: a word or phrase that qualifies the sense of another word; for example, the noun alarm is a modifier of clock in alarm clock and the phrase every day is an adverbial modifier of walks in he walks every day