NOUN (2)

1. a Japanese plant of the family Cruciferae with a thick green root;

2. the thick green root of the wasabi plant that the Japanese use in cooking and that tastes like strong horseradish; in powder or paste form it is often eaten with raw fish;

WordNet (r) 3.0 (2006):

wasabi
    n 1: a Japanese plant of the family Cruciferae with a thick
         green root
    2: the thick green root of the wasabi plant that the Japanese
       use in cooking and that tastes like strong horseradish; in
       powder or paste form it is often eaten with raw fish