cyanobacterium
noun
cy·a·no·bac·te·ri·um ˌsī-ə-nō-bak-ˈtir-ē-əm 
sī-ˌa-nō-
: any of a major group (Cyanobacteria) of photosynthetic bacteria that are single-celled but often form colonies in the form of filaments, sheets, or spheres and are found in diverse environments (such as salt and fresh water, soils, and on rocks)
Note: Like other bacteria, cyanobacteria lack a nuclear membrane and membrane-bound organelles and have cell walls containing peptidoglycan. However, cyanobacteria were more commonly grouped with algae in the past because they possess a type of chlorophyll (chlorophyll a) not found in other bacteria and because they produce oxygen as a by-product of photosynthesis.
called also blue-green alga
cyanobacterial
ˌsī-ə-nō-bak-ˈtir-ē-əl
adjective sī-ˌa-nō-
Example Sentences
Recent Examples on the Web Lichens are actually two organisms working together: a fungus and either alga or cyanobacterium. 
Corryn Wetzel, Smithsonian Magazine, 17 Feb. 2022 One day, another organism—a sort of proto-alga—devoured a cyanobacterium. Elizabeth Kolbert, The New Yorker, 6 Dec. 2021 Called Chroococcidiopsis, this cyanobacterium has a reputation for survival so formidable it is being considered for terraforming Mars. Jennifer Frazer, Scientific American, 4 Mar. 2021 The cyanobacterium was a new species, which Wilde named Aetokthonos hydrillicola in 2014. Erik Stokstad, Science | AAAS, 25 Mar. 2021 In a fateful encounter, a cyanobacterium was engulfed by a eukaryote, a cell that had evolved the capacity for internal organs, and lived on within its membrane. Lucy Jakub, The New York Review of Books, 1 Dec. 2020 His team used a type of cyanobacterium from the genus Synechococcus. Sophie Bushwick, Scientific American, 15 Jan. 2020 Polluted Midwest floodwaters have fed an outbreak of cyanobacterium. Washington Post, 15 July 2019 See More
Corryn Wetzel, Smithsonian Magazine, 17 Feb. 2022 One day, another organism—a sort of proto-alga—devoured a cyanobacterium. Elizabeth Kolbert, The New Yorker, 6 Dec. 2021 Called Chroococcidiopsis, this cyanobacterium has a reputation for survival so formidable it is being considered for terraforming Mars. Jennifer Frazer, Scientific American, 4 Mar. 2021 The cyanobacterium was a new species, which Wilde named Aetokthonos hydrillicola in 2014. Erik Stokstad, Science | AAAS, 25 Mar. 2021 In a fateful encounter, a cyanobacterium was engulfed by a eukaryote, a cell that had evolved the capacity for internal organs, and lived on within its membrane. Lucy Jakub, The New York Review of Books, 1 Dec. 2020 His team used a type of cyanobacterium from the genus Synechococcus. Sophie Bushwick, Scientific American, 15 Jan. 2020 Polluted Midwest floodwaters have fed an outbreak of cyanobacterium. Washington Post, 15 July 2019 See More Word History
Etymology
New Latin
First Known Use
1974, in the meaning defined above
Medical Definition
cyanobacterium
noun
cy·a·no·bac·te·ri·um -bak-ˈtir-ē-əm
plural cyanobacteria
-ē-ə
: any of a major group (Cyanobacteria) of photosynthetic bacteria that produce molecular oxygen and use water as an electron-donating substrate in photosynthesis
called also blue-green alga