The word philtrum has 2 main meanings:
1: noun. The little groove between the bottom of your nose and your top lip.
I have no clue what it is there for, but now
you know what it is called.
2: verb. The art of performing oral sex while shaving. This
originated because some kid at my school with a dirty mind thought it was 'full trim'. The term has since caught on and is now widely recognised.