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

lunule \lu"nule\, n. f., fr. l. lunula, dim. of luna moon.
   1. anat. anything crescent-shaped; a crescent-shaped part
      or mark; a lunula; a lune.
      1913 webster

   2. chem. a lune. see lune.
      1913 webster

   3. zool.
      a a small or narrow crescent.
      b a special area in front of the beak of many bivalve
          shells. it sometimes has the shape of a double
          crescent, but is oftener heart-shaped. see illust. of
          bivalve.
          1913 webster
see also:
lune bivalve 

[2] : WordNet (r) 2.0

lunule
     n : the crescent-shaped area at the base of the human fingernail
         syn: half-moon, lunula
see also:
half-moon lunula 

Lunule >> L Words
Lunule, definition of term: Lunule
lunule_pag1.html