'anaerobe' originates from French, specifically the word 'anaérobie', where 'an-' meant 'without' and 'aérobie' referred to 'air' or 'oxygen'.

'anaérobie' was adopted into English as 'anaerobe' in the late 19th century, and its plural form is 'anaerobes'.

Initially, it meant 'an organism that lives without air (oxygen)', and this meaning has remained the same in modern usage.