A.make close or solid, “τὴν σάρκα” Arist.Pr.865b18, cf. Phld. Mort.8; of winds, νέφεσι π. τὸν οὐρανόν thickens it, Arist.Mete.364b24:—Pass., of vapour and air, ib.342a21, 344b4; “νεφῶν πυκνουμένων” Epicur.Nat.14 Fr.6.
2. contract, condense, opp. μανόω, Arist.Spir. 485a31; of the effect of cold, Id.GA783b1:—Pass., of frozen water, Antipho Soph.29, Arist.Metaph.1042b28, Mu.394a33; ὁ σίδηρος ὑπὸ τοῦ ψυχροῦ πυκνοῦται is contracted, Plu.Alc.6; of steam, “ὁ ἀτμὸς -οῦται καὶ σταγόνες ἀποπίπτουσι” Hp.Flat.8.
II. pack close, ἑωυτούς close their ranks, Hdt.9.18, cf. Ascl.Tact.10.4, Ael.Tact.11.2 (Pass.); “τὸ βάθος ἐπὶ τὸ δεξιόν” Plb.18.24.8; “τὴν τάξιν εἰς βάθος” Plu.Flam.8; σαυτὸν στρόβει πυκνώσας spin yourself round and concentrate your thoughts, Ar.Nu.701 (lyr.):—Pass., to be compressed, “εἰς ἐλάττω τόπον” Arist.Cael.296a18; [“τὴν διάνοιαν] πυκνοῦσθαι εἰκός” Plu.2.715c; τῷ πνεύματι πυκνουμένῳ, i.e. without taking breath, Id.Dem.11.
b. in Logic, πυκνοῦται τὸ μέσον is compressed, becomes closer in signification, Arist.APo.84b35; also πεπύκνωται [ὁ Λυσίας] τοῖς νοήμασι, of a terse style, D.H.Lys.5.
III. close, shut up, “π. τοὺς πόρους” Thphr.Sud.27; “τὸν στόμαχον” Plu.2.687d; “φλέβες πυκνωθεῖσαι” Hp.Salubr.7.
V. intr., become dense, Arist. Mete.344a30, Pr.934b15: in Tactics, “πεπυκνωκότες ἀπὸ τῶν κεράτων ἐπὶ τὰ μέσα” Plb.3.115.6, cf. Ascl.Tact.4.4, Ael.Tact.11.6.