The Collaborative International Dictionary of English v.0.48:
Preventive \Pre*vent"ive\, a. [Cf. F. pr['e]ventif.]
1. Going before; preceding. [Obs.]
Any previous counsel or preventive understanding.
2. Tending to defeat or hinder; obviating; preventing the
access of; as, a medicine preventive of disease.
Physic is either curative or preventive. --Sir T.
Preventive service, the duty performed by the armed police
in guarding the coast against smuggling. [Eng]