/pop lit"ee euhs, pop'li tee"-/ , n. , pl. poplitei /-lit"ee uy', -li tee"uy/ . Anat.
a thin, flat, triangular muscle in back of the knee, the action of which assists in bending the knee and in rotating the leg toward the body.
[ 1695-1705; poplit- (s. of poples ) knee joint, back of the knee + -eus -EOUS ]