Pre·vent·ive a.
 1. Going before; preceding. [Obs.]
    Any previous counsel or preventive understanding.   --Cudworth.
 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. Browne.
 Preventive service, the duty performed by the armed police in guarding the coast against smuggling. [Eng]