double bassoon vs contrabassoon

double bassoon and contrabassoon both are nouns.

Word	Noun	Adjective	Verb	Adverb
double bassoon	Yes	No	No	No
contrabassoon	Yes	No	No	No

As nouns, double bassoon and contrabassoon are synonyms defined as:

double bassoon and contrabassoon: the bassoon that is the largest instrument in the oboe family

Other synonyms of double bassoon include contrafagotto.

double bassoon (noun)	contrabassoon (noun)
the bassoon that is the largest instrument in the oboe family	the bassoon that is the largest instrument in the oboe family