red tide

noun

: seawater discolored by the presence of large numbers of dinoflagellates (as of the genera Karenia, Gymnodinium, and Alexandrium) which typically produce a toxin poisonous especially to many forms of marine vertebrate life and to humans who consume contaminated shellfish compare saxitoxin

Examples of red tide in a Sentence

Recent Examples on the Web

But a surge in deaths in recent years – much of which has been blamed on poor water quality, algae blooms, increasingly busier waters and red tide – has led officials to consider whether the manatee should again be considered endangered. —Christopher Cann, USA TODAY, 30 Dec. 2024

There was a weak El Niño earlier this year, and this wash-up coincided with the recent red tide and Santa Ana winds last week. —Karen Garcia, Los Angeles Times, 21 Nov. 2024

This wash-up coincided with the recent red tide and Santa Ana winds last week, but many variables could lead to these strandings. —Ashley J. Dimella Fox News, Fox News, 20 Nov. 2024

Where Trump gained ground in Southern California A red tide washed through the once strongly liberal Pico-Robertson neighborhood in recent months. —Ryan Fonseca, Los Angeles Times, 10 Dec. 2024

Word History

First Known Use

1904, in the meaning defined above

Rhymes for red tide

• abide
• allied
• applied
• aside
• astride
• azide
• backside
• bankside
• bastide
• bayside
• bedside
• belied

Kids Definition

red tide

noun

: seawater discolored and made poisonous by the presence of large numbers of dinoflagellates

Medical Definition

red tide

noun

: a large area of seawater discolored by the presence of large numbers of dinoflagellates (as of the genera Karenia, Gymnodinium, and Alexandrium) which typically produce toxins poisonous especially to many forms of vertebrate marine life and to humans who consume contaminated shellfish

In simple terms, a red tide is a dinoflagellate population explosion, caused when certain species "bloom," or multiply many times faster than usual.

—Ellen Girardeau

Red tides, the blooms of toxic Karenia brevis algae that appear almost every year in Florida, often lasting for months and turning the ocean red, may be dangerous to asthma sufferers—even if they don't go swimming.

—Nicholas Bakalar

see brevetoxin, saxitoxin, shellfish poisoning