anaerobic

American  

[an-uh-roh-bik, an-ai-] / ˌæn əˈroʊ bɪk, ˌæn ɛə- /

adjective

1. (of an organism or tissue) living in the absence of air or free oxygen.

2. pertaining to or caused by the absence of oxygen.

---

anaerobic British  

/ ˌænɛəˈrəʊbɪk /

adjective

1. (of an organism or process) requiring the absence of or not dependent on the presence of oxygen

2. of or relating to anaerobes

---

anaerobic Scientific  

/ ăn′ə-rō′bĭk /

1. Occurring in the absence of oxygen or not requiring oxygen to live. Anaerobic bacteria produce energy from food molecules without the presence of oxygen.

2. Compare aerobic

---

anaerobic Cultural  

1. A descriptive term for a process, such as fermentation, that can proceed only in the absence of oxygen, or a living thing that can survive only in the absence of oxygen. (Compare aerobic.)

---

Other Word Forms

• anaerobically adverb

Etymology

Origin of anaerobic

First recorded in 1880–85; anaerobe + -ic

Compare meaning

How does anaerobic compare to similar and commonly confused words? Explore the most common comparisons:

• aerobic vs. anaerobic

Explanation

Anaerobic means "without oxygen." Anaerobic bacteria, unlike humans, don't need oxygen to survive. Aerobic means "needing or using oxygen." Think about aerobic activity, also called "cardio," like running, biking, or yes, taking an aerobics class at your local gym. That heart-pumping exercise makes your lungs take in more oxygen to keep you moving. Anaerobic is the opposite of aerobic. It means "without oxygen." Weight lifting is called an anaerobic exercise, because it doesn't require additional oxygen.

Example Sentences

Birds that spent more time together had more similar gut bacteria, especially anaerobic microbes that can only survive in low-oxygen conditions.

From Science Daily • Apr. 13, 2026

"We found that the more social you are with another individual, the more you share similar anaerobic gut bacteria," said Dr. Lee.

From Science Daily • Apr. 13, 2026

"This is an odd adaptation but allows them to perform anaerobic glycolysis," Hadj-Moussa explained.

From Salon • Apr. 20, 2025

In the past few years, more plastic has been going to incinerators and less food waste - which councils are now sending to anaerobic digesters or to be composted.

From BBC • Oct. 15, 2024

Instead the body must immediately produce anaerobic energy.

From "The Boys in the Boat: Nine Americans and Their Epic Quest for Gold at the 1936 Berlin Olympics" by Daniel James Brown