The Collaborative International Dictionary of English v.0.48:

Turban \Tur"ban\ (t[^u]r"ban), n. [OE. turband, turbant,
   tolibant, F. turban, It. turbante, Turk. tulbend, dulbend,
   fr. Per. dulband. Cf. Tulip.]
   1. A headdress worn by men in the Levant and by many Muslims
      of the male sex, consisting of a cap, and a sash, scarf,
      or shawl, usually of cotton or linen, wound about the cap,
      and sometimes hanging down the neck.
      [1913 Webster]

   2. A kind of headdress worn by women.
      [1913 Webster]

   3. (Zool.) The whole set of whorls of a spiral shell.
      [1913 Webster]

WordNet (r) 3.0 (2006):

turban
    n 1: a traditional Muslim headdress consisting of a long scarf
         wrapped around the head
    2: a small round woman's hat [syn: pillbox, toque, turban]