RhymeZone: preformative definitions

Definitions of preformative:

noun: Chiefly in Semitic languages: a formative letter, syllable, etc., at the beginning of a word.
adjective: Of or pertaining to preformation.
adjective: Of a thing: forming or affecting something that comes later.
adjective: (grammar) Chiefly in Semitic languages: of a letter, syllable, etc.: attached to the beginning of a word as a formative element.

(Definitions from Wiktionary)