The Collaborative International Dictionary of English v.0.48:

Minaret \Min"a*ret\, n. [Sp. minarete, Ar. man[=a]rat lamp,
   lantern, lighthouse, turret, fr. n[=a]r to shine.] (Arch.)
   A slender, lofty tower attached to a mosque and surrounded by
   one or more projecting balconies, from which the summon to
   prayer is cried by the muezzin.
   [1913 Webster]

WordNet (r) 3.0 (2006):

minaret
    n 1: slender tower with balconies