Source : Webster's Revised Unabridged Dictionary (1913)

Cid \Cid\, n. [Sp., fr. Ar. seid lord.]
   1. Chief or commander; in Spanish literature, a title of Ruy
      Diaz, Count of Bivar, a champion of Christianity and of
      the old Spanish royalty, in the 11th century.

   2. An epic poem, which celebrates the exploits of the Spanish
      national hero, Ruy Diaz.

Source : WordNet®

CID
     n : the United States Army's principal law enfocement agency
         responsible for the conduct of criminal investigations
         for all levels of the Army anywhere in the world [syn: {Criminal
         Investigation Command}]

Source : Free On-Line Dictionary of Computing

CID
     
        {Caller ID}