Definition of "Lip" :

noun: either the outer margin or the inner margin of the aperture of a gastropod's shell

noun: the top edge of a vessel or other container

noun: either of two fleshy folds of tissue that surround the mouth and play a role in speaking

noun: an impudent or insolent rejoinder

noun: (botany) either of the two parts of a bilabiate corolla or calyx