any of a group of organic compounds consisting of the fats and other substances of similar properties: they are insoluble in water, soluble in fat solvents and alcohol, and greasy to the touch, and are important constituents of living cells
Any of a group of organic compounds, including the fats, oils, waxes, sterols, and triglycerides, that are insoluble in water but soluble in nonpolar organic solvents, are oily to the touch, and together with carbohydrates and proteins constitute the principal structural material of living cells.