oboe vs basset oboe

oboe and basset oboe both are nouns.

Word	Noun	Adjective	Verb	Adverb
oboe	Yes	No	No	No
basset oboe	Yes	No	No	No

As nouns, basset oboe is a hyponym of oboe; that is, basset oboe is a word with a more specific, narrower meaning than oboe:

oboe: a slender double-reed instrument; a woodwind with a conical bore and a double-reed mouthpiece
basset oboe: an oboe pitched an octave below the ordinary oboe

Other hyponyms of oboe include heckelphone, musette pipe, oboe da caccia, oboe d'amore, shawm.

oboe (noun)	basset oboe (noun)
a slender double-reed instrument; a woodwind with a conical bore and a double-reed mouthpiece	an oboe pitched an octave below the ordinary oboe