What does anaerobically mean?
Anaerobically is an adverb describing any process that takes place without the presence of oxygen. It derives from the adjective 'anaerobic', itself built from Greek roots meaning 'without air'. The word appears most often in scientific and technical contexts: microbiologists describe bacteria that grow anaerobically, environmental engineers refer to waste broken down anaerobically in digesters to yield biogas, and sports scientists explain how muscles fuel short bursts of intense effort anaerobically when oxygen supply cannot keep pace with demand. Its direct opposite is 'aerobically', which characterises oxygen-dependent processes such as sustained endurance exercise. Because of its specialised origins, 'anaerobically' carries a formal, technical connotation and is seldom heard outside academic, medical, laboratory, or athletic-training settings. For readers encountering it in news about renewable energy, wastewater treatment, or fitness physiology, understanding the term signals that the process being described runs entirely on chemistry that needs no oxygen.
adverbIn a manner that does not require or occur in the presence of oxygen; used chiefly to describe biological processes, exercise, or conditions occurring without oxygen.
- In a way that does not involve or require oxygen (of biological processes, metabolism, or organisms).
- In a manner relating to intense physical activity fueled without oxygen (of exercise).
"Muscles can generate energy anaerobically during short bursts of intense exertion."
"The bacteria in the digester break down the sludge anaerobically, producing biogas as a by-product."
"Sprinters rely heavily on energy produced anaerobically in their muscles during a hundred-metre dash."
Your muscles can sprint on pure chemistry — no oxygen required — which is exactly what 'anaerobically' describes.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of anaerobically
The word traces back to the Greek elements 'an-' (without) and 'aer' (air), combined with the adjective-forming suffix '-bios' relating to life. The adjective 'anaerobic' was coined in the nineteenth century by French microbiologist Louis Pasteur during his pioneering studies of fermentation, when he demonstrated that some microorganisms live without free oxygen. The adverbial form 'anaerobically' developed from this adjective through standard English derivation. Cognate terms sharing the same root include 'anaerobe' (an organism living without oxygen) and 'anaerobiosis' (the state of such life).
Related word forms
How anaerobically is actually used
Almost exclusively technical and scientific in register; common in microbiology, biochemistry, environmental engineering, and sports science. Rarely encountered in casual conversation.
Easily confused with anaerobically
Aerobically describes processes requiring oxygen, whereas anaerobically describes those occurring without it.