So'cial Democrat'ic par'ty
1. Hist.a political party in Germany advocating a form of social organization based on the economic and political ideology of Karl Marx.
2. any of several European political parties advocating a gradual transition to socialism or a modified form of socialism by and under democratic processes.
3. a U.S. political party, organized about 1897, that joined former members of the Socialist Labor party to form the Socialist party.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.