An anaerobic organism or anaerobe is any organism that does not require oxygen for growth.
From the guardian.co.uk
A member of the Pasteurellaceae family, it is generally aerobic, but can grow as a facultative anaerobe.
From the en.wikipedia.org
Yeast is an example of a facultative anaerobe, which can develop in the presence of oxygen but does not require it.
From the en.wikipedia.org
Organisms not using oxygen for their metabolism, such as anaerobe bacteria, base their metabolism on fermentation.
From the en.wikipedia.org
The challenges of developing the HTS platform for E. histolytica included the facts that it is an anaerobe and that no rapid readout assay is available.
From the nature.com
More examples
An organism (especially a bacterium) that does not require air or free oxygen to live
An organism that can grow in the absence of oxygen or air.
A term borrowed from bacteriology used to refer to a patient with chronically poor lung function whose blood oxygen levels seem too low to be compatible with life, yet who seems to function normally nonetheless.