a white, waxlike substance taken from the oil in the head of a sperm whale or dolphin, used in making cosmetics, ointments, candles, etc.
See spermaceti in American Heritage Dictionary 4
(spûrˌmə-sēˈtē, -sĕtˈē)
nounpl.sper·ma·ce·tis
A white, waxy substance consisting of various esters of fatty acids, obtained from the head of the sperm whale or another cetacean and used for making candles, ointments, and cosmetics.