Webster's Revised Unabridged Dictionary · 1913

Lookout

Lookout , noun

1.
A careful looking or watching for any object or event.
2.
The place from which such observation is made.
3.
A person engaged in watching; a sentinel; a sentry.
4.
Object or duty of forethought and care; responsibility. [Colloquial]
Collocations (1)
on the lookout for , in search of; looking for.