Webster’s Revised Unabridged Dictionary · 1913
Sphincter
Sphinc′ter (sfĭn̲k′tẽr), n. [NL., fr. σφίγγειν to bind tight.] (Anat.) A muscle which surrounds, and by its contraction tends to close, a natural opening; as, the sphincter of the bladder.
Sphinc′ter, a. (Anat.) Of, pertaining to, or designating, a sphincter; as, a sphincter muscle.