prodigal (adj.)

mid-15c., a back-formation from prodigality, or else from Middle French prodigal and directly from Late Latin prodigalis, from Latin prodigus "wasteful," from prodigere "drive away, waste," from pro "forth" (from PIE root *per- (1) "forward") + agere "to set in motion, drive; to do, perform" (from PIE root *ag- "to drive, draw out or forth, move"). First reference is to prodigal son, from Vulgate Latin filius prodigus (Luke xv.11-32). As a noun, "prodigal person," 1590s, from the adjective (the Latin adjective also was used as a noun).