qualifier

Short definition from Wiktionary

Noun

1. 1
   One who qualifies for something, especially a contestant who qualifies for a stage in a competition.
2. 2
   A preliminary stage of a competition.
3. 3
   A word or phrase, such as an adjective or adverb, that describes or characterizes another word or phrase, such as a noun or verb; one that adds or subtracts attributes to another.
4. 4
   A marker that qualifies or modifies another code element.