Cupid's bow

The Cupid's bow is a facial feature where the double curve of a human upper lip is said to resemble the bow of Cupid, the Roman god of erotic love. The peaks of the bow coincide with the philtral columns giving a prominent bow appearance to the lip.

The phrase is common in literature, often used related to speech, and therefore the mouth, as in Venus and Adonis, lines 577–581: