any of a genus (Nostoc) of blue-green algae, having twisted, coiled filaments embedded in a gelatinous material and forming spherical colonies
Webster’s New World College Dictionary, Fourth Edition, compiled by the
editors of Webster’s New World Dictionaries. Copyright © 2010 by Houghton
Mifflin Harcourt. Published by Houghton Mifflin Harcourt. All rights reserved.