la·bi·um 
(lābē-əm)
(lābē-əm)n. pl. la·bi·a (-bē-ə)
1. Anatomy Any of four folds of tissue of the female external genitals.
2. Zoology
a. A liplike structure, such as that forming the floor of the mouth of certain invertebrates, especially insects.
b. The inner margin of the opening of a gastropod shell.
3. Botany One of the liplike divisions of a bilabiate corolla.
[Latin, lip; see leb- in the Appendix of Indo-European roots.]