middle watch vs graveyard watch

middle watch and graveyard watch both are nouns.

Word	Noun	Adjective	Verb	Adverb
middle watch	Yes	No	No	No
graveyard watch	Yes	No	No	No

As nouns, middle watch and graveyard watch are synonyms defined as:

middle watch and graveyard watch: a watch during the night (as from midnight to 8 a.m.)

Other synonyms of middle watch include midwatch, night watch.

middle watch (noun)	graveyard watch (noun)
a watch during the night (as from midnight to 8 a.m.)	a watch during the night (as from midnight to 8 a.m.)