Lewis & Short

căpillus, i, m. (căpillum, i, n., Plaut. Most. 1, 3, 97, acc to Non. p. 198, 20) [a dim. form, akin to caput and Gr. κεφαλή; lit., adj. sc. crinis].

  1. I. Lit., the hair of the head, the hair (while crinis is any hair).
    1. A. Collect. (hence, acc. to Varr, ap. Charis. p. 80 P. in his time used only in the sing.; but the plur is found once in Cic., and since the Aug. poets very freq.) capillus passus, prolixus, circum caput Rejectus neglegenter, Ter. Heaut. 2, 3, 49; cf. id. Phorm. 1, 2, 56: versipellis, Plaut. Pers. 2, 2, 48: compositus (or -um, acc. to Non. l. l.), id. Most. 1, 3, 97; Ter Eun. 4, 3, 4 Ruhnk.; 5, 2, 21: compositus et delibutus, Cic. Rosc. Am. 46, 135: horridus, id. Sest. 8, 19: promissus, long hair, Caes. B. G. 5, 14: longus barbaque promissa, Nep. Dat. 3, 1: horrens. Tac. G. 38: ornatus, Prop. 1, 2, 1: tonsus, Ov. M. 8, 151: niger, Hor. A. P. 37: albus, id. Epod. 17, 23: albescens, id. C. 3, 14, 25: fulvus, Ov. M. 12, 273 (opp. barba): virgines tondebant barbam et capillum patris, Cic. Tusc. 5, 20, 58: capillum et barbam promisisse, Liv. 6, 16, 4; Plin. 11, 39, 94, § 231.
    2. B. A hair (sing. very rare): in imaginem capilli unius sat multorum, Cael. Aur. Tard. 2, 11, 29.
      So plur. (freq.), Cic. Pis. 11, 25; Prop. 1, 15, 11; 3 (4), 6, 9; Hor. C. 1, 12, 41; 1, 29, 7; 2, 11, 15; 3, 20, 14; Quint. 8, 2, 7; 11, 3, 160 (in Ov. M. alone more than fifty times).
  2. II. Transf.
    1. A. The hair of men gen., both of the head and beard: Dionysius cultros metuens tonsorios, candente carbone sibi adurebat capillum, Cic. Off. 2, 7, 25 Beier (cf. id. Tusc. 5, 20, 58: ut barbam et capillum sibi adurerent): ex barbā capillos detonsos neglegimus, Sen. Ep. 92, 34; Suet. Ner. 1.
    2. B. The hair of animals: cuniculi, Cat. 25, 1: apum, Col. 9, 10, 1; Pall. Jun. 7, 7: haedi, Gell. 12, 1, 15: membranae, Pers. 3, 10; cf. Macr. S. 5, 11.
    3. C. The threads or fibres of plants, Phn. 21, 6, 17, § 33: capillus in rosā, id. 21, 18, 73, § 121; hence, capillus Veneris, a plant, also called herba capillaris, maidenhair, App. Herb. 47.