I.= εἶδος, form, Pind., Ar., etc.
2.the look of a thing, as opp. to its reality, Lat. species, γνώμην ἐξαπατῶσ᾽ ἰδέαι outward appearances cheat the mind, Theogn.
3.a kind, sort, nature, Hdt.; ἐφρόνεον διφασίας ἰδέας they conceived two modes of acting, id=Hdt.; τὰ ὄργι᾽ ἐστὶ τίν᾽ ἰδέαν ἔχοντα; what is their nature or fashion? Eur.; καινὰς ἰδέας εἰσφέρειν to bring in new fashions, Ar.; πᾶσα ἰδέα θανάτου every form of death, Thuc.
II.in Logic, = εἶδος, a class, kind, sort, species, Plat.