Some perspective on perspicacious: the word combines the Latin perspicac- (from perspicax meaning “clear-sighted,” which in turn comes from perspicere, “to see through”) with the common English adjective suffix -ious. The result is a somewhat uncommon word used to describe someone (such as a reader or observer) or something (such as an essay or analysis) displaying the perception and understanding of subtleties others tend to miss, such as the distinctions between the words perspicacious, shrewd, sagacious, and astute—something our synonym chooser can help with.