The Collaborative International Dictionary of English v.0.48:

Pimiento \Pi*mien"to\, n. [Sp.]
   The Spanish sweet pepper, the fruit of which is used as a
   vegetable, to stuff olives, etc.; also the fruit itself. Also
   called pimento.
   [Webster 1913 Suppl. +PJC]

WordNet (r) 3.0 (2006):

pimiento
    n 1: plant bearing large mild thick-walled usually bell-shaped
         fruits; the principal salad peppers [syn: sweet pepper,
         bell pepper, pimento, pimiento, paprika, sweet
         pepper plant, Capsicum annuum grossum]
    2: fully ripened sweet red pepper; usually cooked [syn:
       pimento, pimiento]