lookout man vs sentinel

lookout man and sentinel both are nouns.

Word	Noun	Adjective	Verb	Adverb
lookout man	Yes	No	No	No
sentinel	Yes	No	No	No

As nouns, lookout man and sentinel are synonyms defined as:

lookout man and sentinel: a person employed to keep watch for some anticipated event

Other synonyms of lookout man include lookout, picket, scout, sentry, spotter, watch.

lookout man (noun)	sentinel (noun)
a person employed to keep watch for some anticipated event	a person employed to keep watch for some anticipated event