look out

Short definition from Wiktionary

Verb

1. 1
   To be vigilant and aware often as an imperative to alert a person to danger.
2. 2
   To find by looking: to hunt out.
3. 3
   To be facing.
4. 4
   Used other than figuratively or idiomatically: see look, out.
5. 5
   Clipping of look out for (someone)
6. 6
   To be supportive or protective of someone.

Noun

1. 1
   Alternative spelling of lookout.