from
The Collaborative International Dictionary of English v.0.48
Labium \La"bi*um\, n.; pl. L. {Labia}, E. {Labiums}. [L.]
1. A lip, or liplike organ.
[1913 Webster]
2. The lip of an organ pipe.
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3. pl. (Anat.) The folds of integument at the opening of the
vulva.
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4. (Zool.)
(a) The organ of insects which covers the mouth beneath,
and serves as an under lip. It consists of the second
pair of maxill[ae], usually closely united in the
middle line, but bearing a pair of palpi in most
insects. It often consists of a thin anterior part
(ligula or palpiger) and a firmer posterior plate
(mentum).
(b) Inner margin of the aperture of a shell.
[1913 Webster]