Definitions of hunger from commonly-used references include:
A desire or need for food; any appetite, strong desire, or craving. (Dirckx, 2001)
The uneasy or painful sensation caused by want of food; craving appetite. Also the exhausted condition caused by want of food. (Oxford American Dictionary, 1980)
A physiological need for food; the consequence of food deprivation; strong desire for something; feel the need to eat; have a craving, appetite, strong desire for; be hungry; go without food. (WordNet, n.d.)
A sensation resulting from lack of food, characterized by dull or acute pain referred to the epigastrium or lower part of the chest. Usually accompanied by weakness and an overwhelming desire to eat. Hunger pains coincide with powerful contractions of the stomach. Hunger is distinguished from appetite in that the latter is a pleasant sensation based on previous experience that causes one to seek food for the purpose of tasting and enjoying it; to have a strong desire. (Thomas, 1989)
HUNGER:
Hunger is not just the need to eat; hunger, as the word is used by food and health experts can be defined as the continuing deprivation in a person of the food needed to support a healthy life. The more technical term is under nutrition. Over time, hunger slows physical and mental development in children and leaves them more vulnerable to illness and disease. For example, respiratory and diarrhea infections are common in undernourished children, and even diseases of vitamin A deficiency, which can cause blindness, anemia, caused by iron deficiency and goiter due to iodine deficiency.