LIPID

n. any of a number of fats or fat-like compounds that are insoluble in water (Biochemistry)

Lipids can be broadly defined as any fat-soluble (hydrophobic), naturally-occurring molecules. The term is more-specifically used to refer to fatty-acids and their derivatives (including tri-, di-, and monoglycerides and phospholipids) as well as other fat-soluble sterol-containing metabolites such as cholesterol.
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Lipid /lip·id/ any of a heterogeneous group of fats and fatlike substances, including fatty acids, neutral fats, waxes, and steroids, which are [more]Lipid - Community and Resources

Noun
1. an oily organic compound insoluble in water but soluble in organic solvents; essential structural component of living cells (along with proteins and carbohydrates)
(synonym) lipide, lipoid
(hypernym) macromolecule, supermolecule
(hyponym) fat

Fatty substance.