Definition of Lipid

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Lipid: Another word for "fat." (Please see the various meanings of Fat.) A lipid is more formally defined as a substance such as a fat, oil or wax that dissolves in alcohol but not in water. Lipids contain carbon, hydrogen and oxygen but have far less oxygen proportionally than carbohydrates.

Lipids are an important part of living cells. Together with carbohydrates and proteins, lipids are the main constituents of plant and animal cells.

Cholesterol and triglycerides are lipids. Lipids are easily stored in the body. They serve as a source of fuel and are an important constituent of the structure of cells.

Lipids include fatty acids, neutral fats, waxes and steroids (like cortisone). Compound lipids (lipids complexed with another type of chemical compound) comprise the lipoproteins, glycolipids and phospholipids.

Etymology: Whereas the everyday term "fat" comes from the Old English (from "faett" meaning crammed or adorned), the more scientific term "lipid" comes from the Greek "lipos" which referred to animal fat or vegetable oil. The derivation of a biomedical term from another tongue such as Greek, Latin or French lends it a certain "je ne sais quoi" (something that cannot be easily expressed), a touch of continental class.