Lipid: Another word for “fat.” A lipid is chemically defined as a substance that is insoluble in water and soluble in alcohol, ether, and chloroform.
Lipids are an important component of living cells. Together with carbohydrates and proteins, lipids are the main constituents of plant and animal cells.
Source: www.medicinenet.com/script/main/art.asp?articlekey=4168