Lewis & Short

calcar, āris, n. [for carcar; cf. Sanscr. kar, wound; and Lat. calx].

  1. I. Lit., a spur as worn on the heel: calcaria dicta, quia in calce hominis ligantur, ad stimulandos equos, Isid. Orig. 20, 16, 6 (class. in prose and poetry; esp. freq. trop.): calcari quadrupedem agitare, Plaut. As. 3, 3, 118: incendere equum calcaribus, to spur one’s horse, Hirt. B. G. 8, 48; so, concitare, Liv. 2, 6, 8; Curt. 7, 4, 18: stimulare, Val. Max. 3, 2, 9: subdere equo calcaria, Liv. 2, 20, 2; Curt. 3, 13, 8; 7, 2, 4: calcaribus subditis, Liv. 4, 19, 4; 4, 33, 7; Curt. 4, 16, 6: equi fodere calcaribus armos, Verg. A. 6, 881: calcaribus auferre equum, Sil. 10, 280.
    1. B. Trop., spur, stimulus, incitement: calcaribus ictus amoris, *Lucr. 5, 1074: dicebat Isocrates se calcaribus in Ephoro, contra autem in Theopompo frenis uti solere, Cic. de Or. 3, 9, 36: alter frenis eget, alter calcaribus, id. Att. 6, 1, 12; cf. id. Brut. 56, 204; Quint. 2, 8, 11; 10, 1, 74: anticipate atque addite calcar, Varr. ap. Non. p. 70, 13; * Hor. Ep. 2, 1, 217: immensum gloria calcar habet, Ov. P 4, 2, 36.
      So also of the driving winds: ventus calcar admovere, Varr. ap. Non. p. 451, 29.
      Prov.: addere calcaria sponte currenti, to spur a willing horse, Plin. Ep. 1, 8, 1.
  2. II. Transf., the spur on the leg of the cock, Col. 8, 2, 8.