algae Definition

a plant or plantlike organism of any of several phyla, divisions, or classes of chiefly aquatic usually chlorophyll-containing nonvascular organisms of polyphyletic origin that usually include the green, yellow-green, brown, and red algae in the eukaryotes and especially formerly the cyanobacteria in the prokaryotes

any of a division (Phaeophyta) of variable mostly marine algae with chlorophyll masked by brown pigment

any of a division (Chrysophyta) of marine and freshwater algae (such as diatoms) containing yellowish-green to golden-brown pigments that obscure the chlorophyll —called also chrysophyte, golden alga