The Collaborative International Dictionary of English v.0.48:

Vanilla \Va*nil"la\, n. [NL., fr. Sp. vainilla, dim. of Sp.
   vaina a sheath, a pod, L. vagina; because its grains, or
   seeds, are contained in little pods.]
   [1913 Webster]
   1. (Bot.) A genus of climbing orchidaceous plants, natives of
      tropical America.
      [1913 Webster]

   2. The long podlike capsules of Vanilla planifolia, and
      Vanilla claviculata, remarkable for their delicate and
      agreeable odor, for the volatile, odoriferous oil
      extracted from them; also, the flavoring extract made from
      the capsules, extensively used in confectionery,
      perfumery, etc.
      [1913 Webster]

   Note: As a medicine, vanilla is supposed to possess powers
         analogous to valerian, while, at the same time, it is
         far more grateful.
         [1913 Webster]

   Cuban vanilla, a sweet-scented West Indian composite shrub
      (Eupatorium Dalea).

   Vanilla bean, the long capsule of the vanilla plant.

   Vanilla grass. Same as Holy grass, under Holy.
      [1913 Webster]

WordNet (r) 3.0 (2006):

Vanilla planifolia
    n 1: a climbing orchid bearing a podlike fruit yielding vanilla
         beans; widely cultivated from Florida southward throughout
         tropical America [syn: vanilla orchid, Vanilla
         planifolia]