Lewis & Short

subtīlĭtas (supt-), ātis, f. [subtilis], fineness, thinness, slenderness, minuteness (syn. tenuitas).

  1. I. Lit. (mostly post-Aug.; not in Cic.): linearum, Plin. 35, 10, 36, § 82: ferramentorum, the keen edge, sharpness, id. 28, 9, 41, § 148: inenarrabilis florum, id. 21, 1, 1, § 1: muliebris, Vitr. 4, 1 med.: immensa animalium, Plin. 11, prooem. 1, § 1: caelandi fingendique ac tingendi, id. 35, prooem. § 1: umoris, id. 2, 65, 65, § 163.
  2. II. Trop.
    1. A. In gen., keenness, acuteness, penetration, definiteness, exactness, subtlety, etc. (class.; syn.: acumen, sollertia): sententiarum, Cic. N. D. 2, 1, 1: disputandi, id. Tusc. 3, 23, 56: ea subtilitas, quam Atticam appellant, id. Brut. 17, 67: subtilitas sermonis, id. Rep. 1, 10, 16: credunt plerique militaribus ingeniis subtilitatem deesse, Tac. Agr. 9: ingens, Petr. 31: tanta, id. 38; Sen. Ep. 113, 1: Aristoteles, vir immensae subtilitatis, Plin. 18, 34, 77, § 335; cf.: litterarum, id. 2, 108, 112, § 247: geometrica, id. 2, 65, 65, § 164: perversa grammaticorum, id. 35, 3, 4, § 13: subtilitas parcimoniae compendia invenit, id. 17, 22, 35, § 171: picturae summa suptilitas, id. 35, 9, 36, § 67: inutilis, Sen. Ep. 65, 16: quaedam inutilia et inefficacia ipsa subtilitas reddit, id. ib. 82, 24: nimia, id. ib 88, 43.
    2. B. In partic., in rhet., plainness, simplicity, absence of ornament: orationis subtilitas imitabilis quidem illa videtur esse existimanti, sed nihil est experienti minus, Cic. Or. 23, 76; id. Brut. 84, 291: suavitatem Isocrates, subtilitatem Lysias, vim Demosthenes habuit, id. de Or. 3, 7, 28: subtilitas et elegantia scriptorum, id. Fam. 4, 4, 1.