the male germ cell, found in semen, which penetrates the ovum, or egg, of the female to fertilize it: typically it consists of a head containing a large nucleus, a small midsection, and a whiplike tail used for locomotion
See spermatozoon in American Heritage Dictionary 4
(spər-mătˌə-zōˈŏnˌ, -ən, spûrˌmə-tə-)
nounpl.sper·mat·o·zo·a(-zōˈə)
The mature fertilizing gamete of a male organism, usually consisting of a round or cylindrical nucleated cell, a short neck, and a thin motile tail. Also called sperm cell, zoosperm.