string bass vs bass fiddle

string bass and bass fiddle both are nouns.

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

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

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

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

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