Origin: 1200–50;Middle English, aphetic variant of apert < Old French < Latinapertus open (past participle of aperīre; see aperient); in Middle English and Old French, influenced by Old Frenchaspert < Latinexpertusexpert
c.1300 (implied in pertly), "evident, unconcealed," aphetic form of apert "open, frank," from O.Fr. apert, from L. apertus, pp. of aperire "to open" (see overt). Sense of "saucy, bold" first recorded late 14c. Less pejorative meaning "lively, brisk, in good spirits" (c.1500)
survives in U.S. dial. peart (with M.E. alternative spelling).