stearin, fat that is the triglyceride of stearic acid, CH₃(CH₂)₁₆CO₂H, i.e., the tristearate ester of glycerol. It is a white crystalline solid at ordinary temperatures and is insoluble in water and very slightly soluble in alcohol. It is found (often mixed with palmitin) in many hard fats and oils, e.g., in tallow, suet, butterfat, cottonseed oil, and olive oil. It is used in making soap and candles.

Stearin (or /ˈstɪɹɪn/) is a glyceryl ester of stearic acid, derived from animal fats created as a byproduct of processing beef. It is used as tallow in the manufacture of candles and soap. In the manufacture of soap, it is mixed with a sodium hydroxide solution in water. The following reaction gives glycerin and soap (sodium stearate): C₃H₅(C₁₈H₃₅O₂)₃ + 3NaOH → C₃H₅(OH)₃ + 3C₁₇H₃₅COONa

Stearin is also used in conjunction with Aluminum Flakes to help in the grinding process in making Dark Aluminum powder. It is a side product during extraction of cod liver oil removed during chilling process at temperature below -5°C.