The Collaborative International Dictionary of English v.0.48:

Ananas \A*na"nas\, n. [Sp. ananas, from the native American
   name.] (Bot.)
   The pineapple (Ananassa sativa).
   [1913 Webster]

WordNet (r) 3.0 (2006):

Ananas
    n 1: a genus of tropical American plants have sword-shaped
         leaves and a fleshy compound fruits composed of the fruits
         of several flowers (such as pineapples) [syn: Ananas,
         genus Ananas]
    2: large sweet fleshy tropical fruit with a terminal tuft of
       stiff leaves; widely cultivated [syn: pineapple, ananas]