bos'n vs bosun

bos'n and bosun both are nouns.

Word	Noun	Adjective	Verb	Adverb
bos'n	Yes	No	No	No
bosun	Yes	No	No	No

As nouns, bos'n and bosun are synonyms defined as:

bos'n and bosun: a petty officer on a merchant ship who controls the work of other seamen

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

bos'n (noun)	bosun (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