embouchure

noun, plural em·bou·chures [ahm-boo–shoo rz; ahm-boo-shoo rz; French ahn-boo-shyr] /ˌɑm bʊˈʃʊərz; ˈɑm bʊˌʃʊərz; French ɑ̃ buˈʃür/.

the mouth of a river.
the opening out of a valley into a plain.
Music.
1. the mouthpiece of a wind instrument.
2. the adjustment of a player’s mouth to such a mouthpiece.

noun

the mouth of a river or valley
music
1. the correct application of the lips and tongue in playing a wind instrument
2. the mouthpiece of a wind instrument

1760, in musical sense, from French embouchure “river mouth, mouth of a wind instrument,” from en- “in” (see en- (1)) + bouche “mouth” (see bouche).