Lewis & Short

1. plānus, a, um, adj. [for placnus; root plac-; Gr. πλακοῦς; cf. 2. plaga, planca], even, level, flat, plane (class.; cf. aequor).

  1. I. Lit.: facilis et plana via, Plaut. Trin. 3, 2, 19: cum duae formae praestantes sint, ex solidis globus, ex planis circulus aut orbis, Cic. N. D. 2, 18, 47: planum et aequabile corpus universitatis, id. Univ. 5: planus et aequus locus, id. Caecin. 17, 50: litus, Caes. B. G. 4, 23: carina, id. ib. 3, 13: pisces, flat-fish, Plin. 9, 20, 37, § 73: aedificia, quae plano pede instituuntur, on level ground, Vitr. 6, 11: postquam jacuit planum mare, Juv. 12, 62: planā faciem contundere palmā, flat, id. 13, 128.
    Comp.: aditus planior, Liv. 34, 29.
    Sup.: planissimus locus, Cic. Agr. 2, 35, 96.
    1. B. Subst.: plānum, i, n., level ground, a plain: aciem in planum deducit, Sall. J. 49, 6: per planum ire, Ov. A. A. 2, 243: cadere in plano, id. Tr. 3, 4, 17: in planum deferre aliquid, Sen. Tranq. 10, 6: castra in plano erant, Flor. 4, 12, 59: de plano, on level ground, Dig. 13, 6, 5; Aus. Grat. Act. 21: ad planiora, Vulg. Judic. 1, 34.
      In partic., jurid. t. t.: e plano or de plano, on level ground, below, not on the bench, i. e. out of court, extrajudicially: aut e plano aut e quaesitoris tribunali, Suet. Tib. 33: custodiae non solum pro tribunali, sed et de plano audiri possunt, Dig. 48, 18, 18; ib. 37, 1, 3.
  2. II. Trop.
    1. A. Lowly, inconsiderable, humble (post-Aug.): haec magnanimitas melius in tribunali, quam in plano conspicitur, shows better in one of high than of low station, Sen. Clem. 1, 5, 3: fortunam suam in planum deferre, id. Tranq. 10, 6: de plano, without difficulty, easily (poet.): hoc tibi de plano possum promittere, Lucr. 1, 411.
    2. B. Plain, clear, distinct, intelligible (class.): satin’ haec sunt tibi plana et certa! Plaut. Pers. 2, 2, 1: narrationes, Cic. Top. 26, 97: conjectatio, Plin. 2, 7, 5, § 22: pol planum id quidem est, it is plain, clear, evident, Plaut. Capt. 3, 4, 32: planum facere, to make plain, clear, or intelligible, to set forth, Cic. Verr. 1, 18, 56; 2, 1, 10, § 27; 2, 1, 20, § 52; 2, 5, 64, § 165: planum facere multis testibus, id. ib. 1, 14, 40: planum facere atque probare, Lucr. 2, 932.
    3. C. Easy, free from danger: illam viam vitae, quam ante praecipitem et lubricam esse ducebat, huic planae et stabili praeponendam esse, Cic. Flac. 42, 105.
      Hence, adv.: plānē, plainly, evenly; trop., simply, clearly, distinctly, intelligibly.
      1. 1. Lit. (class.): videre, Plaut. Trin. 4, 3, 64: scribere, id. As. 4, 1, 10: scire, id. Truc. 2, 6, 9: plane loqui, Plaut. Am. 2, 1, 30: plane et dilucide loqui, Cic. de Or. 1, 32: plane et perspicue expedire aliquid, id. Fin. 3, 5, 19: plane et Latine loqui, to speak plainly, right out, without circumlocution, id. Phil. 7, 6, 17.
        Comp.: quo pacto excludi potis est planius, quam, etc., Plaut. Truc. 2, 8, 5: planius dicere (opp. dicere obscurius), Cic. de Or. 2, 80, 329: planius atque apertius dicere, id. Rosc. Com. 14, 43: quid, hoc planius egissem, si, etc., id. Verr. 2, 1, 10, § 27: ostendere, Plin. 18, 28, 68, § 273.
        Sup.: apertissime planissimeque explicare, Cic. Verr. 2, 2, 64, § 156.
    4. B. Transf., wholly, entirely, completely, quite (class.), Plaut. Ep. 3, 4, 55: perdidisti mulierem, id. Ps. 4, 7, 115: illam plane amo, id. Capt. 3, 4, 6: carere sensu communi, Hor. S. 1, 3, 66: quod reliquos coheredes convenisti, plane bene, you have acted quite right, Cic. Att. 13, 6, 2: illud plane moleste tuli, quod, etc., id. Fam. 3, 10, 11: non plane par, Auct. Her. 4, 20, 28: ex rebus penitus perspectis, planeque cognitis, Cic. de Or. 1, 23, 108: propemodum, vel plane potius, id. Brut. 97, 332: explicari mihi tuum consilium plane volo, ut penitus intellegam, thoroughly, id. Att. 8, 12, 1: planissime perii, Plaut. Truc. 2, 6, 67: plane perfecteque eruditus, Cic. Brut. 81, 282: plane atque omnino rem defuisse, id. ib. 59, 214: plane cum, particularly as, Inscr. Grut. 208; cf.: et plane quid rectum esset diutius cogitare malui, Cic. Att. 8, 12, 3.
      1. 2. By all means, assuredly: eo acrius te rogo ut plane ad nos advoles, Cic. Att. 2, 24, 5 fin.
      2. 3. In partic., in affirmative answers, certainly, to be sure, exactly so (anteclass.): ego et domi privatus sum et perii. Ge. Plane istuc est, Plaut. Truc. 2, 7, 57; id. Ps. 4, 7, 73: De. Etiam argentum est ultro objectum, ut sit, qui vivat, dum aliud aliquid flagitii conficiat Ge. Planissume, Ter. Phorm. 5, 2, 4.
      3. 4. Besides, but (late Lat.), Dig. 9, 2, 7; 32, 1, 52.