Lewis & Short

lăbĭa or lăbĕa, ae, f., and lăbĭum, ii, n. [Gr. λάπτω; Lat. lambo, labrum, labeo; cf. Germ. Lippe; Engl. lip],

  1. I. a lip (form labia, ante- and post-class. for labrum; labium, also post-Aug.: Verrius Flaccus sic distinxit, modica esse labra, labia immodica et inde labiones dici, Charis. p. 79 P.): dejecta labia, App. M. 3, p. 140.
    In neutr.: labium, Seren. ap. Non. 210, 21.
    More freq. in plur.: age tibicen: refer ad labias tibias, Plaut. Stich. 5, 4, 41: tremulus labeis demissis, Ter. Eun. 2, 3, 44; Nigid. ap. Gell. 10, 4, 4: labiae pendulae, App. M. 3, p. 140.
    Form labea, Pompon. ap. Non. 456, 43: labearum ductu, Gell. 18, 4, 6.
    In neutr.: salivosa labia, App. Mag. p. 313: labiorum fissuris mederi, Plin. 29, 3, 11, § 46: ulcera labiorum, id. 34, 11, 27, § 115; Quint. 11, 3, 160 dub.; Lact. Opif. D. 10, 13; Just. 1, 10, 15; 15, 3, 4.
    Prov.: labiis ductare aliquem, to ridicule, make game of one, Plaut. Mil. 2, 1, 15.
  2. II. Transf., the axle or some other part of an oil-press: labiam bifariam facito, Cato, R. R. 20, 2.