sentinel vs lookout

sentinel and lookout both are nouns.

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

As nouns, sentinel and lookout are synonyms defined as:

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

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

sentinel (noun)	lookout (noun)
a person employed to keep watch for some anticipated event	the act of looking out
	a structure commanding a wide view of its surroundings
	an elevated post affording a wide view
	a person employed to keep watch for some anticipated event