a wax, liquid at body temperature, obtained from the head of a sperm whale or bottlenose whale. Spermaceti was used chiefly in ointments, cosmetic creams, fine wax candles, pomades, and textile finishing; later it was used for industrial lubricants. The substance was named in the mistaken belief that it was the coagulated semen of the whale.

The fluid contained in the spermaceti organ of the whale's head was removed to obtain crude sperm oil. The spermaceti was separated from the oil by chilling in a process whalers called wintering; it congealed as a white crystalline, waxy solid. Chemically, pure spermaceti consists principally of cetyl palmitate and other esters (ester) of fatty acids (fatty acid) with fatty alcohols (alcohol) and melts at about 44 °C (111 °F). The former official unit of illumination, the candlepower (candela), was defined as the light given off by a candle of pure spermaceti burning at a rate of 7.776 grams (120 grains) per hour.