Source : Webster's Revised Unabridged Dictionary (1913)

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

Source : WordNet®

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