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  • cyanobacteria
    cyanobacteria
    plural noun
    a widely distributed group of photosynthetic bacteria, occurring singly or in colonies in terrestrial and aquatic habitats: often mistakenly referred to as algae, especially when called by their most common misnomer, blue-green algae .
  • Cyanobacteria
    Cyanobacteria
    noun
    the phylum, or subkingdom, that comprises the cyanobacteria.

cyanobacteria

1 American  
[sahy-uh-noh-bak-teer-ee-uh, sahy-an-oh-] / ˌsaɪ ə noʊ bækˈtɪər i ə, saɪˌæn oʊ- /

plural noun

singular

cyanobacterium

  1. Microbiology. a widely distributed group of photosynthetic bacteria, occurring singly or in colonies in terrestrial and aquatic habitats: often mistakenly referred to as algae, especially when called by their most common misnomer, blue-green algae .

Cyanobacteria 2 American  
[sahy-uh-noh-bak-teer-ee-uh, sahy-an-oh-] / ˌsaɪ ə noʊ bækˈtɪər i ə, saɪˌæn oʊ- /

noun

Microbiology.

  1. the phylum, or subkingdom, that comprises the cyanobacteria.

cyanobacteria British  
/ ˌsaɪənəʊbækˈtɪərɪə /

plural noun

  1. Former name: blue-green algae.  a group of photosynthetic bacteria (phylum Cyanobacteria ) containing a blue photosynthetic pigment

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Etymology

Origin of cyanobacteria1

First recorded in 1975–80; cyano- 1 + bacteria

Origin of Cyanobacteria2

See cyanobacteria ( def. )

Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

Multicellular cyanobacteria evolved gradually from single-celled ancestors, gaining complexity over time.

From Science Daily • Apr. 20, 2026

The findings suggest that soon after cyanobacteria began producing oxygen, other organisms evolved the machinery to consume it.

From Science Daily • Feb. 18, 2026

Microbes living near cyanobacteria could have quickly absorbed the oxygen being released.

From Science Daily • Feb. 18, 2026

The beauty of the sky contrasts sharply with the water, sometimes blue, but often a murky green from cyanobacteria or stained black.

From BBC • Jan. 29, 2026

The research team isolated eight strains of heat-tolerant cyanobacteria from the Bo Khlueng hot spring in Ratchaburi Province, Thailand.

From Science Daily • Jan. 13, 2026

Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023

Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.