- any of numerous groups of chlorophyll-containing, mainly aquatic eukaryotic organisms ranging from microscopic single-celled forms to multicellular forms 100 feet (30 meters) or more long, distinguished from plants by the absence of true roots, stems, and leaves and by a lack of nonreproductive cells in the reproductive structures: classified into the six phyla Euglenophyta, Crysophyta, Pyrrophyta, Chlorophyta, Phaeophyta, and Rhodophyta.
Compare blue-green algae.
Origin of algae
< New Latin, plural of Latin alga seaweed
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018
Examples from the Web for algal
Earlier this month, Toledo, Ohio, watched its municipal water supply descend into an undrinkable stew of algal toxins.Are Water Filters B.S.?
August 19, 2014
The algal host cells lie in the medulla, just below the upper cortex.
The chains of cells are usually badly broken up, and the nature of the algal host is, therefore, difficult to distinguish.
The algal hosts are usually Dactylococcus or Polycoccus, and both hosts are sometimes found in the same thallus.
It was, therefore, most desirable to devise a method of ridding the bed of algal growth without injuring the cress.
This only killed the algal growth with which the particles of copper came in contact and left the main body of alg unaffected.
- unicellular or multicellular organisms formerly classified as plants, occurring in fresh or salt water or moist ground, that have chlorophyll and other pigments but lack true stems, roots, and leaves. Algae, which are now regarded as protoctists, include the seaweeds, diatoms, and spirogyra
C16: from Latin, plural of alga seaweed, of uncertain origin
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
Word Origin and History for algal
(plural), 1794, from alga (singular), 1550s, from Latin alga "seaweed," of uncertain origin, perhaps from a PIE root meaning "to putrefy, rot."
Online Etymology Dictionary, © 2010 Douglas Harper
- Any of various chiefly aquatic, eukaryotic, photosynthetic organisms, ranging in size from single-celled forms to the giant kelp.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
The most familiar algae are the greenish scum that collects in still water.
Algae supply a considerable part of the world's oxygen.
The New Dictionary of Cultural Literacy, Third Edition Copyright © 2005 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.