midwatch vs graveyard watch

midwatch and graveyard watch both are nouns.

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

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

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

Other synonyms of midwatch include middle watch, night watch.

midwatch (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.)