1. A lip or liplike structure; such as, the one forming the roof of the mouth in insects.
2. The outer margin of the opening of a gastropod shell.

A triangular rim of fibrocartilage, the base of which is fixed to the margin of the acetabulum (cup-shaped socket of the hip joint; from Latin an acetabulum, "a vinegar cup" or "a cup"), deepening its cavity.

A triangular rim of fibro cartilage, the base of which is fixed to the circumference of the glenoid cavity of the scapula, deepening it.

A mouth part composed of the labrum (lip) and epipharynx (structure which overlaps the mouth of certain insects) and usually elongate (more length than width).