Sphinc"ter (?), n. [NL., fr. &?;&?;&?; 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.

Sphinc"ter (?), n. [NL., fr. &?;&?;&?; 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.

• (anatomy) A ringlike band of muscle that surrounds a bodily opening, constricting and relaxing as required for normal physiological functioning.