bass fiddle vs bass viol

bass fiddle and bass viol both are nouns.

Word	Noun	Adjective	Verb	Adverb
bass fiddle	Yes	No	No	No
bass viol	Yes	No	No	No

As nouns, bass fiddle and bass viol are synonyms defined as:

bass fiddle and bass viol: largest and lowest member of the violin family

Other synonyms of bass fiddle include bull fiddle, contrabass, double bass, string bass.

bass fiddle (noun)	bass viol (noun)
largest and lowest member of the violin family	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