I. measured motion, time, whether in sound or motion, Democr.15c; = ἡ τῆς κινήσεως τάξις, Pl.Lg.665a, cf. 672e; “ὁ ῥ. ἐκ τοῦ ταχέος καὶ βραδέος, ἐκ διενηνεγμένων πρότερον, ὕστερον δὲ ὁμολογησάντων γέγονε” Id.Smp.187b, cf. Suid. s.v.; rhythm, opp. μέτρον and ἁρμονία, Ar. Nu.638 sq., Pl.R.397b, 398d, 601a, Arist.Rh.1403b31; “λόγοι μετὰ μουσικῆς καὶ ῥυθμῶν πεποιημένοι” Isoc.15.46; of Prose rhythm, Arist.Rh.1408b29, D.H.Comp.17: defined by Aristox.Rhyth.1, Aristid.Quint.1.13.
2. special phrases: ἐν ῥυθμῷ in time, of dancing, marching, etc., “βαίνειν ἐν ῥ.” Pl.Lg.670b, cf. X.An.5.4.14; “ὀρχεῖσθαι” Id.Cyr.1.3.10; ἐν τῷ ῥ. ἀναπνεῖν respire regularly, Arist.Pr.882b1; so “σωζόμενος ῥ.” A.Ch.797 (lyr.); “μετὰ ῥυθμοῦ βαίνοντες” Th.5.70; ῥυθμὸν χορείας ὑπάγειν keep time, Ar.Th.956 (lyr.); θάττονα ῥυθμὸν ἐπάγειν play in quicker time, X.Smp.2.22; “πυρριχίῳ δρόμῳ καὶ ῥυθμῷ” Hdn.4.2.9, cf. Plb.4.20.6: pl., paces, Alcid.Soph. 17.
II. measure, proportion or symmetry of parts, at rest as well as in motion, κατὰ τὸν αὐτὸν ῥ. Pl.Lg.728e.
III. generally, proportion, arrangement, order, “ῥυθμῷ τινι” E.Cyc.398 (codd., but θ᾽ ἑνὶ is prob.); οὐκ ἀπὸ ῥυσμοῦ εἰκάζω not without reason, Call. Epigr.44.5.
IV. state or condition of anything, temper, disposition, Thgn.964 (coupled with ὀργή and τρόπος)“; οἷος ῥυσμὸς ἀνθρώπους ἔχει” Archil.66.7; “ὅσοι χθονίους ἔχουσι ῥυσμοὺς καὶ χαλεπούς” Anacr. 74; μένει . . χρῆμ᾽ οὐδὲν ἐν ταὐτῷ ῥ. Eup.356.
V. form, shape of a thing, Democr.5i; identified by Arist. with σχῆμα, Metaph.985b16, 1042b14; μετέβαλον τὸν ῥ. τῶν γραμμάτων changed the form or shape of the letters, Hdt.5.58; of Chian boots, Hp.Art.62; of the shape of a cup, Alex.59; of a breastplate, X.Mem.3.10.10; [τοῦ θυσιαστηρίου] LXX 4 Ki.16.10; “Αὐτονόας ῥ. ωὑτός” Theoc.26.23; so of the natural features of a country, D.P.271,620; structure of a substance, κεγχροειδὲς τῷ ῥ., τῷ ῥ. σπογγῶδες, Dsc.5.77,118.