What is "kathetal"

Kathetal \Kath"e*tal\, a. [Gr. ? a perpendicular line. See Cathetus.] (Math.) Making a right angle; perpendicular, as two lines or two sides of a triangle, which include a right angle.

a. (context mathematics English) Making a right angle; perpendicular, as two lines or two sides of a triangle, which include a right angle.