(n.) One who, or that which, modifies.

IC analysis agent alterant alterative alterer appositive attribute attributive catalyst catalytic agent complement construction modifier cutting deep structure direct object ferment filler form-function unit function immediate constituent analysis indirect object innovationist innovator introducer leaven levels modificator object phrase structure precursor predicate qualifier ranks shallow structure slot slot and filler strata structure subject surface structure syntactic analysis syntactic structure syntactics syntax tagmeme transformer transmogrifier underlying structure word arrangement word order yeast