Stearic acid comes from many animal and vegetable fats and oils. It is a waxy solid. Its name comes from the Greek word stéar (genitive: stéatos), which means tallow. Stearic acid is useful as an ingredient in making candles, soaps, plastics, oil pastels and cosmetics, and for softening rubber. Stearic acid is used to harden soaps, particularly those made with vegetable oil.