contrabassoon vs double bassoon

contrabassoon and double bassoon both are nouns.

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

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

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

Other synonyms of contrabassoon include contrafagotto.

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