perpendicular (adj.) Copy link Outline 1. dīrectus (straight, in gen. sense)2. perpendĭcŭlāris, e (late; and to be strictly confined to geometrical lang.) • perpendicular (adj.): 1. dīrectus (straight, in gen. sense): a ditch with p. sides, fossa d. lateribus, Caes. B. G. 7, 72: more precisely, directus ad perpendiculum, ib. 4, 17 (directe, adv.: Long.). 2. perpendĭcŭlāris, e (late; and to be strictly confined to geometrical lang.): Front. Goes. p. 32. Phr.: to make strictly p., ad libellam (perpendiculum) dirigere, Vitr. 3, 4 (3), 5.