preventive

Short definition from Wiktionary

Adjective

1. 1
   Preventing, hindering, or acting as an obstacle to.
2. 2
   Carried out to deter military aggression.
3. 3
   Slowing the development of an illness; prophylactic.
4. 4
   Going before; preceding.

Noun

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