bass viol vs bull fiddle

bass viol and bull fiddle both are nouns.

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

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

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

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

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