n. [ NL., fr. &unr_;&unr_;&unr_; to bind tight. ] (Anat.) A muscle which surrounds, and by its contraction tends to close, a natural opening; as, the sphincter of the bladder. [ 1913 Webster ]
a. (Anat.) Of, pertaining to, or designating, a sphincter; as, a sphincter muscle. [ 1913 Webster ]