string bass vs bull fiddle

string bass and bull fiddle both are nouns.

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

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

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

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

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