Source : Webster's Revised Unabridged Dictionary (1913)

Eu \Eu\ [Gr. ? well, orig. neut. of ? good; prob. connected with
   Skr. su, from the same root as E. is; or with Skr. vasu good,
   prob. fr. the same root as E. was.]
   A prefix used frequently in composition, signifying well,
   good, advantageous; -- the opposite of dys-.

Source : WordNet®

Eu
     n 1: a bivalent and trivalent metallic element of the rare earth
          group [syn: {europium}, {atomic number 63}]
     2: an international organization of European countries formed
        after World War II to reduce trade barriers and increase
        cooperation among its members; "he took Britain into
        Europe" [syn: {European Union}, {European Community}, {EC},
         {European Economic Community}, {EEC}, {Common Market}, {Europe}]