stear

Stear is not a standalone chemical; rather, stear- is a combining form originating from the Greek stear, meaning fat or tallow. In chemistry and biochemistry, the form stear- appears in the names of fatty acids, glycerides, and related esters to indicate fat-derived character. The most prominent example is stearic acid, also called octadecanoic acid, a saturated fatty acid with 18 carbon atoms.

Stearic acid is common in many animal and plant fats and is solid at room temperature with a high melting point. In biological and industrial contexts, stear- appears in derivatives such as stearoyl-, stearate, and stearin, which respectively designate fatty acyl fragments, salts or esters of stearic acid, and the solid triglyceride component of fats.

Stearin refers to the solid fraction of fats and oils obtained during rendering or fractionation and has historical significance in candle making and soap production. Modern uses of stearic-derived compounds include cosmetics, lubricants, and polymer articles, where stearate salts and esters act as surfactants or stabilizers.

This root is generally encountered as a prefix or combining form rather than a standalone substance, and precise meaning depends on the compound name in which it appears.