precaution

Short definition from Wiktionary

Noun

1. 1
   Previous caution or care; caution previously employed to prevent misfortune or to secure good.
2. 2
   A measure taken beforehand to ward off evil or secure good or success; a precautionary act.

Verb

1. 1
   To warn or caution beforehand.
2. 2
   To take precaution against.