A.let down, perpendicular, “πρὸς τὴν γῆν” Arist.Mech.857b28; καθέταν is f.l. in Alc. 39: usu. Subst.,
1. κάθετος (sc. γραμμή), ἡ, perpendicular, Arist.Mete. 373a11, Ti.Locr.98b, etc., al.; plumb-line, Aen.Tact.32.6; πρὸς τὴν κ. δ᾽ ἐμετρήθη Epigr. ap. Plu.Aem.15; κατὰ κάθετον vertically, perpendicularly, Ph.Bel.69.22, Heliod. ap. Orib.49.13.1, Placit.2.24.1, Apollod. Poliorc.155.9; κατὰ κ. τοῦ ὀμφαλοῦ vertically below, Paul.Aeg.6.50; πρὸς κ. Plu.2.938a; perpendicular height, τριῶν ἥμισυ σταδίων ἔχειν τὴν κ. Str.8.6.21.