| Noun | 1. | Cyanophyceae - photosynthetic bacteria found in fresh and salt water, having chlorophyll a and phycobilins; once thought to be algae: blue-green algaeCyanophyta, division Cyanophyta - prokaryotic organisms sometimes considered a class or phylum or subkingdom; coextensive with the Cyanophyceae: cyanobacteria (blue-green algae) blue-green algae, cyanobacteria - predominantly photosynthetic prokaryotic organisms containing a blue pigment in addition to chlorophyll; occur singly or in colonies in diverse habitats; important as phytoplankton class - (biology) a taxonomic group containing one or more orders | |