philtrum

The story

1. Ancient Greek · derived fromφῐ́λτρον“a love charm; the dimple in the upper lip”
2. Latin · borrowed fromphiltrum“a love potion”
3. English todayphiltrum

Borrowed from the Latin philtrum (“a love potion”), from Ancient Greek φῐ́λτρον (phĭ́ltron, “a love charm; the dimple in the upper lip”). Doublet of philter.