Preventive

Full definition of preventive

Adjective

1. Preventing, hindering, or acting as an obstacle to.
2. Carried out to deter military aggression.
3. Slowing the development of an illness; prophylactic.
• Sir Thomas BrownePhysic is either curative or preventive.
4. (obsolete) Going before; preceding.
• CudworthAny previous counsel or preventive understanding.

Noun

1. (nonstandard) A thing that prevents, hinders, or acts as an obstacle to.
2. (nonstandard) A thing that slows the development of an illness.
3. A contraceptive, especially a condom.

Alternative forms

• preventative

Usage notes

Many speakers prefer to use preventive in adjective senses and preventative in noun senses.

http://www.wsu.edu/~brians/errors/nonerrors.html#preventive