philtre (n.)

also philter, "love potion, potion supposed to have the power of exciting sexual love," 1580s, from Middle French philtre (1560s), from Latin philtrum (plural philtra) "love potion," from Greek philtron "a love-charm," properly philētron, literally "to make oneself beloved," from philein "to love" (from philos "loving;" see philo-) + instrumental suffix -tron.