preventive vs preemptive

preventive is a noun but preemptive is not a noun.

Word	Noun	Adjective	Verb	Adverb
preventive	Yes	Yes	No	No
preemptive	No	Yes	No	No

preventive (noun)	preemptive (noun)
remedy that prevents or slows the course of an illness or disease
an agent or device intended to prevent conception
any obstruction that impedes or is burdensome

preventive (adjective)	preemptive (adjective)
tending to prevent or hinder	designed or having the power to deter or prevent an anticipated situation or occurrence
preventing or contributing to the prevention of disease