"Anaerobic" refers to processes that occur without the presence of oxygen. This term is often used in biology to describe certain types of respiration that organisms, such as bacteria and yeast, can perform to generate energy. Anaerobic respiration typically results in byproducts like lactic acid or ethanol, depending on the organism and conditions. In addition to biological contexts, anaerobic conditions can also be found in environments like swamps or deep ocean floors, where oxygen is limited. These conditions are crucial for the breakdown of organic matter and play a significant role in nutrient cycling within ecosystems.