1640s, from Middle French prostate, from Medieval Latin prostata "the prostate," from Greek prostates (aden) "prostate (gland)," from prostates "leader, ruler, guardian; one standing in front," from proistanai "set before," from pro- "before" (see pro-) + histanai "cause to stand" from PIE root *sta- "to stand" (see stet). So called from its position at the base of the bladder.