boatswain vs bo's'n

boatswain and bo's'n both are nouns.

Word	Noun	Adjective	Verb	Adverb
boatswain	Yes	No	No	No
bo's'n	Yes	No	No	No

As nouns, boatswain and bo's'n are synonyms defined as:

boatswain and bo's'n: a petty officer on a merchant ship who controls the work of other seamen

Other synonyms of boatswain include bo'sun, bos'n, bosun.

boatswain (noun)	bo's'n (noun)
a petty officer on a merchant ship who controls the work of other seamen	a petty officer on a merchant ship who controls the work of other seamen