Webster's Revised Unabridged Dictionary (1913):

Gamete \Gam"ete\ (g[a^]m"[=e]t; g[.a]*m[=e]t"; the latter
   usually in compounds), n. [Gr. gameth` wife, or game`ths
   husband, fr. gamei^n to marry.] (Biol.)
   A sexual cell or germ cell; a conjugating cell which unites
   with another of like or unlike character to form a new
   individual. In Bot., gamete designates esp. the similar sex
   cells of the lower thallophytes which unite by conjugation,
   forming a zygospore. The gametes of higher plants are of two
   sorts, sperm (male) and egg (female); their union is
   called fertilization, and the resulting zygote an o["o]spore.
   In Zo["o]l., gamete is most commonly used of the sexual cells
   of certain Protozoa, though also extended to the germ cells
   of higher forms.

WordNet (r) 2.0:

gamete
     n : a mature sexual reproductive cell having a single set of
         unpaired chromosomes