Source : Webster's Revised Unabridged Dictionary (1913)

Cetyl \Ce"tyl\, n. [Gr. ? whale + -yl.] (Chem.)
   A radical, {C16H33}, not yet isolated, but supposed to exist
   in a series of compounds homologous with the ethyl compounds,
   and derived from spermaceti.

Hexdecyl \Hex"de*cyl\, n. [Hex- + decyl.] (Chem.)
   The essential radical, {C16H33}, of hecdecane.