Lewis & Short

1. constantĭa, ae, f. [1. constans].

  1. I. A firm standing, steadiness, firmness, immutability, unchangeableness, constancy, perseverance (in good prose; esp. freq. in Cic.): (stellarum) perennes cursus atque perpetui cum admirabili incredibilique constantiā, Cic. N. D. 2, 21, 55; cf. id. ib. § 56, and 3, 9, 23: dictorum conventorumque, id. Off. 1, 7, 23; cf. promissi, id. Att. 4, 19 (17), 1: tantā constantiā vocis atque voltūs, Nep. Att. 22, 1: perseverantia constantiaque oppugnandi, Auct. B. Alex. 26.
  2. II. Trop., agreement, harmony, symmetry, consistency: testimoniorum, Auct. Her. 2, 6, 9: ordo et constantia et moderatio dictorum omnium atque factorum, Cic. Off. 1, 28, 98: non ex singulis vocibus philosophi spectandi sunt, sed ex perpetuitate atque constantiā, id. Tusc. 5, 10, 31: in quibus (orationibus) forsitan magis requiratur constantia, id. Clu. 51, 141; cf.: constantiae causā, for consistency’s sake, id. ib. 2, 2, 5: quae autem est inter augures conveniens et conjuncta constantia? id. Div. 2, 39, 82: officii, id. Sull. 1, 2.
      1. 2. Firmness of character, steadfastness, immovability, constancy, self-possession: is, qui moderatione et constantiā quietus animo est sibi ipse placatus, ut nec tabescat molestiis, etc., Cic. Tusc. 4, 17, 37; cf. id. ib. 4, 17, 38: Catoni cum incredibilem tribuisset natura gravitatem, eamque ipse perpetuā constantiā roborasset semperque in proposito susceptoque consilio permansisset, etc., id. Off. 1, 31, 112: si soceri Scauri constantiam (ceperis), id. Verr. 1, 17, 52: benevolentiam, nonardore quodam amoris, sed stabilitate potius et constantiā judicemus, id. Off. 1, 15, 47: firmamentum constantiae est fides, id. Lael. 18, 65: hinc constantia, illinc furor, id. Cat. 2, 11, 25; id. Sest. 41, 88; id. Phil. 7, 4, 14; id. Off. 1, 28, 98; Nep. Thras. 1, 1; Hor. Epod. 15, 15; Liv. 42, 62, 11: de eorum fide constantiāque dubitatis? Caes. B. G. 7, 77; Brut. ap. Cic. Ep. ad Brut. 1, 16, 10: animi, Ov. M. 11, 293: morum, Tac. H. 3, 86; id. A. 13, 30 fin.; Sen. Const. Sap. 1, 1 sqq.: sunt et alia ingenita quaedam adjumenta vox, latus, patiens laboris valetudo, constantia, decor, i. e. natural firmness, intrepidity, Quint. prooem. § 27 Meyer.; cf. id. 6, prooem. § 11; 12, 5, 2.
        Acc. to the notions of the Stoics, = εὐπάθεια; in plur.: sic quattuor perturbationes sunt, tres constantiae ( = εὐπαθείας τρεῖς, Diog. L. 7, 115), Cic. Tusc. 4, 6, 14; cf. Aug. Civ. Dei, 14, 8.