'Preventative' definitions:

Definition of 'preventative'

From: WordNet
adjective
Tending to prevent or hinder [syn: preventive, preventative] [ant: permissive]
adjective
Preventing or contributing to the prevention of disease; "preventive medicine"; "vaccines are prophylactic"; "a prophylactic drug" [syn: preventive, preventative, prophylactic]
noun
Remedy that prevents or slows the course of an illness or disease; "the doctor recommended several preventatives" [syn: preventive, preventative, prophylactic]
noun
Any obstruction that impedes or is burdensome [syn: hindrance, hinderance, hitch, preventive, preventative, encumbrance, incumbrance, interference]
noun
An agent or device intended to prevent conception [syn: contraceptive, preventive, preventative, contraceptive device, prophylactic device, birth control device]

Definition of 'Preventative'

From: GCIDE
  • Preventative \Pre*vent"a*tive\, n. That which prevents; -- incorrectly used instead of preventive. [1913 Webster]