Definition of "alga" []

• Any of various chiefly aquatic, eukaryotic, photosynthetic organisms, ranging in size from single-celled forms to the giant kelp. Algae were once considered to be plants but are now classified separately because they lack true roots, stems, leaves, and embryos. (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "The alga, which is native to the Pacific Ocean, first showed up three years ago in"
• "In one, domestic sewage is utilized to produce an alga which is then used for fish culture."
• "Potter was originated the idea that lichens were a symbiosis between a fungus and an alga."