Also kath-. [a. L. cathetus, a. Gr. κάθετος (sc. γραμμή) a perpendicular line, κάθετος adj. ‘let down, perpendicular,’ f. καθιέναι to let down.] A straight line falling perpendicularly on another straight line or surface.
1571. Digges, Pantom., IV. Def. 20. It shal be named the Axis or Kathetus of that body.
1622. Peacham, Gentl. Exerc., I. xi. (1634), 38. Every thing seemeth downward in the water by reason of the fall of the other beames in the Catheton or perpendicular.
1676. Baker, in Rigaud, Corr. Sci. Men (1841), II. 13. Having the cathetus of the first and the common hypotenuse given, to find the cathetus of the simple angle.
1751. Chambers, Cycl., s.v., Cathetus of Incidence … a right line drawn from a radiant point, perpendicular to the reflecting line, or the plane of the speculum, or mirror. Cathetus of Reflexion, [etc.].
1817. Colebrooke, Algebra, 59. The cóti or upright is the cathetus.
1875. Gwilt, Archit., Gloss. Cathetus, a perpendicular line passing through the centre of a cylindrical body as a baluster or a column. It is also a line falling perpendicularly, and passing through the centre or eye of the volute of the Ionic capital.
