[ ˌspə:mə'si:ti , -'sɛti ]
■ noun a white waxy substance obtained from an organ in the head of the sperm whale, which focuses acoustic signals and aids in the control of buoyancy, and was formerly used in candles and ointments.
Origin
C15: from med. L., from late L. sperma 'sperm' + ceti 'of a whale' (from Gk kētos 'whale'), from the belief that it was whale spawn.