Lewis & Short

ăcūmĕn, ĭnis, n. [acuo], a point to prick or sting with; diff. fr. cacumen, which designates merely the summit or extremity of a thing, Doed. Syn. 2, 108.

  1. I. Lit.: tum clupei resonunt et ferri stridit acumen, Enn. ap. Prisc. p. 838 P. (Ann. v. 369 ed. Vahl.): coni, Lucr. 4, 431: nasi, id. 6, 1193 (i.e. the pointed contraction of the nose before death; cf. Bentl. ad Hor. S. 1, 3, 29): stili, Cic. de Or. 1, 33: ferrum Diana volanti abstulerat jaculo: lignum sine acumine venit, Ov. M. 8, 353; 3, 84.
    Hence, also, the sting of an animal: scorpii, Cic. Arat. 685:auspicium ex acuminibus, a military omen of victory, when the spears stuck in the ground suddenly begin to burn or shine at the points, Cic. Div. 2, 36, 77, and id. N. D. 2, 3; cf. Liv. 22, 1; 43, 13.
    In Plin., of the taste: sharpness or pungency, 14, 20, 25.
  2. II. Fig., of the mind, like acies.
    1. A. Acuteness, shrewdness, keenness, acumen: sermonis leporem, ingeniorum acumen, dicendi copiam, Cic. Fl. 4; so Nep. Alc. 11; Plin. 2, 27, 27, § 97.
      Also without a gen.: ubi est acumen tuum? Cic. Tusc. 1, 6; so Lucr. ap. Cic. Fam. 5, 14, 2: Empedocles an Stertinium deliret acumen, Hor. Ep. 1, 12, 20.
      Poet. also in plur.: serus Graecis admovit acumina chartis, Hor. Ep. 2, 1, 161.
    2. B. Cunning, subtlety: argutiae et acumen Hyperidis, Cic. Or. 31; so id. de Or. 2, 63.
      Also in plur.: dialectici ipsi se compungunt suis acuminibus, id. de Or. 2, 38: meretricis acumina, Hor. Ep. 1, 17, 55.
      Hence,