[1] : The Collaborative International Dictionary of English v.0.48

labrum \la"brum\, n.; pl. l. labra, e. labrums. l.
   1. a lip or edge, as of a basin.
      1913 webster

   2. zool.
      a an organ in insects and crustaceans covering the upper
          part of the mouth, and serving as an upper lip. see
          illust. of hymenoptera.
      b the external margin of the aperture of a shell. see
          univalve.
          1913 webster
see also:
labra labrums hymenoptera univalve 

[2] : WordNet (r) 2.0

labra
     see labrum
see also:
labrum 

Labra >> L Words
Labra, definition of term: Labra
labra_pag1.html