Search Result for "red tide":
Wordnet 3.0

NOUN (1)

1. seawater that is discolored by large numbers of certain dinoflagellates that produce saxitoxin; 



WordNet (r) 3.0 (2006):

red tide
    n 1: seawater that is discolored by large numbers of certain
         dinoflagellates that produce saxitoxin