bass viol vs viola da gamba

bass viol and viola da gamba both are nouns.

Word	Noun	Adjective	Verb	Adverb
bass viol	Yes	No	No	No
viola da gamba	Yes	No	No	No

As nouns, bass viol and viola da gamba are synonyms defined as:

bass viol and viola da gamba: viol that is the bass member of the viol family with approximately the range of the cello

Other synonyms of bass viol include gamba.

bass viol (noun)	viola da gamba (noun)
viol that is the bass member of the viol family with approximately the range of the cello	viol that is the bass member of the viol family with approximately the range of the cello
largest and lowest member of the violin family