A craving for food or other substance necessary to bodily activity. Hunger for food is supposed to be directly produced by strong contractions of the stomach, which occur when it is empty, or nearly so. (See also THIRST.)

Air hunger is an instinctive craving for oxygen resulting in breathlessness, either when a person ascends to great heights where the pressure of air is low, or in some diseases such as pneumonia and DIABETES MELLITUS which affect the body's METABOLISM and therefore its need for oxygen – an essential constituent in this process.