A Dictionary of Music and Musicians/Embouchure
EMBOUCHURE. The part of a musical instrument applied to the mouth; and hence used to denote the disposition of the lips, tongue, and other organs necessary for producing a musical tone.
To the embouchure are due, not only the correct quality of the sound produced, but also certain slight variations in pitch, which enable the player to preserve accurate intonation. In many instruments, such especially as the French horn and the Bassoon, almost everything depends upon the embouchure.[ W. H. S. ]