What would best describe an organism that does not require oxygen for survival?

An organism that does not require oxygen for survival is best described as an anaerobe. Anaerobes are capable of living and growing in environments devoid of oxygen. There are different types of anaerobes, including obligate anaerobes, which are harmed or even killed by the presence of oxygen, and facultative anaerobes, which can survive with or without oxygen but prefer to use oxygen for more efficient energy production.

In contrast, aerobes are organisms that require oxygen in order to grow, while microaerophiles thrive in environments with lower oxygen levels than those present in the atmosphere. Therefore, the definition of an anaerobe is specific to its lack of oxygen dependence, making it the most accurate descriptor for organisms that do not need oxygen for survival.