Lewis & Short

anceps (once ancipes, Plaut. Rud. 4, 4, 114; cf. Charis, pp. 67 and 96 P.; Prisc. p. 754 P.; with this form cf. procapis, Paul. ex Fest. p. 225 Müll., and Corss. Ausspr. II. pp. 398, 591; abl. sing. always ancipiti), cĭpĭtis, adj. [an-caput; cf. Paul. ex Fest. p. 19 Müll.].

  1. I. Lit., that has two heads, twoheaded (cf.: biceps, praeceps, etc.; so only in the poets): Janus, Ov. M. 14, 334; so id. F. 1, 95 (cf.: Janus bifrons, Verg. A. 7, 180).
    Hence also of a mountain which has two summits, two-peaked: acumen, Ov. M. 12, 337.
  2. II. In gen.
  1. A.
    1. 1. Of an object whose qualities have significance in two respects, double, that extends on two opposite sides (while duplex is an object that exists in separate forms, twice. Thus anceps sententia is an opinion which wavers, fluctuates between two decisions, while duplex sententia is a twofold opinion): Post altrinsecus ancipes securiculast, the axe cuts on two sides, is two-edged, Plaut. Rud. 4, 4, 114; so, ferrum, Lucil. ap. Non. p. 245, 17, and Lucr. 6, 168: securis, Ov. M. 8, 397 al.
      Also, poet., of the contrast between great heat and cold: Ancipiti quoniam mucroni utrimque notantur, since things are marked by double point, i. e. one at one, another at the other end, Lucr. 2, 520: bestiae quasi ancipites in utrāque sede viventes, amphibious animals, Cic. N. D. 1, 37; so in the histt. freq. of an attack, a contest, etc., on two different sides, Caes. B. G. 7, 76: ita ancipiti proelio diu atque acriter pugnatum est, double, because contending with enemies both in front and in the rear, id. ib. 1, 26 Herz.; so id. B. C. 3, 63; Nep. Them. 3, 3: periculum, Sall. J. 38, 5: ancipitem pugnam hostibus facere, double, as given by horse and foot, Tac. A. 6, 35: ancipiti metu et ab cive et ab hoste, twofold, Liv. 2, 24; so, anceps terror, id. 34, 21; Tac. Agr. 26: tumultus, Liv. 32, 30: tela, shot or hurled from both sides, id. 37, 11: ancipitia munimenta, on two sides, id. 5, 1 al.
      1. 2. Trop., twofold: propter ancipitem faciendi dicendique sapientiam, Cic. de Or. 3, 16: ancipites viae rationesque et pro omnibus et contra omnia disputandi, id. ib. 3, 36: adferre ancipitem curam cogitandi, a twofold care of thought, id. Off. 1, 3, 9; so Tac. A. 2, 40: jus anceps, the uncertainties of law, Hor. S. 2, 5, 34 al.
    2. B. Wavering, doubtful, uncertain, unfixed, undecided (the prevalent signif. in Cic.): anceps fatorum via, Cic. Somn. Scip. 2: incertus exitus et anceps fortuna belli, id. Marcell. 5: anceps proelii fortuna, Tac. H. 3, 18: oraculum, Liv. 9, 3: proelium, id. 2, 62, and Tac. H. 3, 22; so esp. freq.: ancipiti Marte pugnare, to contend without deciding the contest, Liv. 7, 29; 21, 1 al.: causa anceps, Cic. de Or. 2, 44: genus causarum anceps, id. Inv. 1, 15, 20 (cf.: genus causarum dubium, Auct. ad Her. 1, 3: dubium vel anceps, Quint. 4, 1, 10): fides, uncertain, wavering, fidelity, Curt. 3, 8; so also, ancipites animi, Luc. 9, 46.
      Also ellipt.: Lucanus an Apulus, anceps, doubtful whether, etc., * Hor. S. 2, 1, 34.
    3. C. Dangerous, hazardous, perilous, critical (post-Aug.; esp. freq. in Tac.; never in Cic.): viae, Ov. M. 14, 438: loca, Nep. Dat. 7, 3: dubiā et interdum ancipiti fortunā, Vell. 2, 79: anceps periculum, Tac. A. 4, 59: ancipites morbi corporis, Plin. 7, 45, 46, § 149: cujus (Antonii) operā ex ancipiti morbo convaluerat, Suet. Aug. 59: Ideo et purgationibus (labruscum) ancipitem putant, Plin. 23, 1, 14, § 20: vox pro re publicā honesta, ipsi anceps, pernicious, Tac. H. 1, 5: adulatio anceps si nulla et ubi nimia est, id. A. 4, 17.
      So subst., danger, hazard, peril, = periculum, discrimen: dubiā suorum re in anceps tractus vim legionum implorabat, Tac. A. 4, 73: seu nihil militi seu omnia concederentur, in ancipiti res publica, id. ib. 1, 36: scelus inter ancipitia probatum, id. ib. 11, 26; 14, 22: facilius inter ancipitia clarescunt, id. G. 14: nova ambigua ancipitia malebat, id. H. 2, 86: inter ancipitia deterrimum est media sequi, id. ib. 3, 40.
      Note: Comp., sup., and adv. not used.