To make stealthy observations in (a country or place) from hostile motives. Also with out, esp. in to spy out the land; frequently figurative.

To observe carefully. Obsolete.

absol. or intransitive. To look steadily, watch, keep a look out; to act as a spy. archaic.

To be on the look out; to keep a person or thing in sight, so as to be aware of any movement or change.

intransitive. To watch.

To keep watch vigilantly; to be on the lookout.

slang. transitive. To observe; to take particular notice of; to watch; also, to find out or discover by observation, to detect. Also absol. or intrans…

colloquial (originally U.S.). to keep one's eyes peeled and variants: to remain alert, be on the lookout; to watch carefully for. Cf. to keep one's e…

U.S. colloquial. to skin one's eyes: to remain alert, be on the lookout. Cf. to keep one's eyes skinned at skinned, adj. phrases.

to peel one's eyes: to be watchful and alert, to keep one's eyes peeled (peeled, adj. 1b).

A look or glance (at something or in a certain direction). Now rare except in slang phrase to take sights, to observe, to watch.