Noun
labret (plural labrets)
A body piercing consisting of an adornment attached to the lip. [from 1843]
Synonyms: Mao, (informal) tongue pillar
Labret piercings are pierced with a labret stud and can pierced in the center or off-center. Source: Internet
Moss, Madonna L. "George Catlin among the Nayas: Understanding the practice of labret wearing on the Northwest Coast." Source: Internet