stoplight vs go-ahead

stoplight and go-ahead both are nouns.

Word	Noun	Adjective	Verb	Adverb
stoplight	Yes	No	No	No
go-ahead	Yes	No	No	No

As nouns, go-ahead is a hyponym of stoplight; that is, go-ahead is a word with a more specific, narrower meaning than stoplight:

Other hyponyms of stoplight include green light, red light, yellow light.

stoplight (noun)	go-ahead (noun)
a visual signal to control the flow of traffic at intersections	readiness to embark on bold new ventures
a red light on the rear of a motor vehicle that signals when the brakes are applied to slow or stop	a signal to proceed