The Collaborative International Dictionary of English v.0.48:

Ligula \Lig"u*la\ (l[i^]g"[-u]*l[.a]), n.; pl. L. Ligul[ae]
   (-l[=e]), E. Ligulas (-l[.a]z). [L., a little tongue. See
   Ligule.]
   1. (Bot.) See Ligule.
      [1913 Webster]

   2. (Zool.)
      (a) The central process, or front edge, of the labium of
          insects. It sometimes serves as a tongue or proboscis,
          as in bees. [See Illust. under Labium, and
          Hymenoptera.]
      (b) A tongue-shaped lobe of the parapodia of annelids. See
          Parapodium.
          [1913 Webster] Ligulate