The Collaborative International Dictionary of English v.0.48:

Hanukka \Ha"nuk*ka\, or Hanukkah \Ha"nuk*kah\, n. [Heb.
   khanukk[=a]h.]
   The Jewish Feast of the Dedication, instituted by Judas
   Maccab[ae]us, his brothers, and the whole congregation of
   Israel, in 165 b. c., to commemorate the dedication of the
   new altar set up at the purification of the temple of
   Jerusalem to replace the altar which had been polluted by
   Antiochus Epiphanes of Syria (--1 Maccabees i. 58, iv. 59).
   The feast, which is mentioned in John x. 22, is held for
   eight days (beginning with the 25th day of Kislev,
   corresponding to December), and is celebrated everywhere,
   chiefly as a festival of lights, by the Jews. [Also spelled
   Chanuka.]

   Syn: Chanukah, Festival of Lights, Feast of Dedication, Feast
        of the Dedication.
        [Webster 1913 Suppl.]