Lewis & Short

pĕnē̆tro, āvi, ātum, 1, v. a. and n. [root pa- of pasco; v. penates].

  1. I. Act.
    1. A. To put, place, or set any thing into any thing (ante- and post-class.; v. Brix ad Plaut. Trin. 1, 2, 109).
      1. 1. Lit.: penetrare pedem intra aedes, Plaut. Men. 5, 2, 64; 2, 3, 49: quo illic homo foras se penetrat ex aedibus? to betake one’s self, go in any direction, id. Trin. 2, 2, 1: me ad pluris penetravi, id. ib. v. 14: se in fugam, to take to flight, id. Am. 1, 1, 94: in eam (specum) me penetro et recondo, Gell. 5, 14, 18.
        To enter, penetrate: ea intra pectus se penetravit potio, Plaut. Truc. 1, 1, 23.
        In the same sense, mid.: quae penetrata queunt sensum progignere acerbum, having entered, having penetrated, Lucr. 4, 670; 1246.
      2. 2. Trop.: Labeo Antistius in grammaticam sese atque dialecticam litterasque antiquiores altioresque penetraverat, had penetrated into, Gell. 13, 10, 1.
    2. B. Aliquid, to pierce into any thing; to enter, penetrate any thing (poet. and in post-Aug. prose).
      1. 1. Lit., Lucr. 4, 894: (semen) penetrare locos nequit, id. 4, 1246: vox aures penetrat, id. 4, 613: hominem cum vini vis penetravit Acris, id. 3, 476: Illyricos sinus, Verg. A. 1, 243: nave Aegyptum, Suet. Caes. 52: mediae cryptam Suburrae, Juv. 5, 106.
        Pass.: ut (India) penitus nequeat penetrari, Lucr. 2, 539: penetratae cum victoriā Media, Albania, etc., Vell. 2, 40, 1: penetrata limina montis, Stat. S. 4, 6, 104: iter L. Lucullo penetratum, Tac. A. 15, 27.
      2. 2. Trop.: id Tiberii animum altius penetravit, Tac. A. 1, 69; cf. id. ib. 3, 4.
        With subject-clause: tum penetrabat eos, posse haec, etc., it entered their thoughts, it occurred to them, Lucr. 5, 1262.
  2. II. Neutr., to enter, penetrate into any place or thing, betake one’s self (class.; cf.: pervado, permano).
    1. A. Lit.: in palaestram, Plaut. Bacch. 1, 1, 32: sub terras, Cic. Verr. 2, 4, 48, § 107: ad os Pelusii, Curt. 4, 1, 29: in ipsum portum, Cic. Verr. 2, 5, 37, § 96: in castra hostium, Liv. 2, 12, 3: in artissimas fauces, Curt. 5, 3, 17: ad urbes, Cic. Prov. Cons. 13, 32: per angustias, id. Tusc. 1, 20, 45: intra vallum, Liv. 39, 31: in urbem, id. 2, 53: cum eo penetrasset, thus far, Nep. Chabr. 4: astra per caelum penetrantia, Cic. Univ. 9: penetrat vox ad aures, Ov. M. 12, 42: usque ad nares, Cels. 7, 7.
      Impers. pass.: in eam speluncam penetratum cum signis est, Liv. 10, 1.
    2. B. Trop.: Romuli animus haec ipsa in templa penetravit, Cic. Rep. 6, 22, 24: hominum ratio in caelum usque penetravit, id. N. D. 2, 61, 163: nulla res magis penetrat in animos, id. Brut. 38, 142: penetrare ad sensum judicis opinionemque, id. Part. 36: quo non ars penetrat? Ov. A. A. 3, 291: in provincias quoque grammatica penetraverat, Suet. Gram. 3.