late 15c., "capable of being seen through" (a sense now obsolete), from Latin perspicuus "transparent, clear, evident," from perspicere "look through, look closely at" (see perspective). From 1580s as "clear to the understanding, not obscure or ambivalent." Related: Perspicuously; perspicuousness.
a perspicuous argument
perspective
Perspex
perspicacious
perspicacity
perspicuity
perspicuous
perspiration
perspire
persuadable
persuade
persuasible