rock gunnel vs butterfish

rock gunnel and butterfish both are nouns.

Word	Noun	Adjective	Verb	Adverb
rock gunnel	Yes	No	No	No
butterfish	Yes	No	No	No

As nouns, rock gunnel and butterfish are synonyms defined as:

rock gunnel and butterfish: slippery scaleless food fish of the northern Atlantic coastal waters

Other synonyms of rock gunnel include Pholis gunnellus.

rock gunnel (noun)	butterfish (noun)
slippery scaleless food fish of the northern Atlantic coastal waters	small marine fish with a short compressed body and feeble spines
	slippery scaleless food fish of the northern Atlantic coastal waters
	any of numerous small flat Atlantic food fish having smooth skin