The Collaborative International Dictionary of English v.0.48:

Eau de Cologne \Eau` de Co*logne"\ [F. eau water (L. aqua) + de
   of + Cologne.]
   Same as Cologne.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Cologne \Co*logne"\, n. [Originally made in Cologne, the French
   name of K["o]ln, a city in Germany.]
   A perfumed liquid, composed of alcohol and certain aromatic
   oils, used in the toilet; -- called also cologne water and
   eau de cologne.
   [1913 Webster]

WordNet (r) 3.0 (2006):

eau de cologne
    n 1: a perfumed liquid made of essential oils and alcohol [syn:
         cologne, cologne water, eau de cologne]