red tide: Meaning and Definition of

red' tide'

Pronunciation: [key]
  1. a brownish-red discoloration of marine waters caused by the presence of enormous numbers of certain microscopic flagellates, esp. the dinoflagellates, that often produce a potent neurotoxin that accumulates in the tissues of shellfish, making them poisonous when eaten by humans and other vertebrates.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.