democrat (n.)

1790, "adherent or advocate of democracy," with reference to France, from French démocrate (18c., opposed to aristocrate), back-formation from démocratie (see democracy); formally revived in U.S. as a political party affiliation 1798, with a capital D. As a shortening of this, Demo (1793) is older than Dem (c. 1840). An earlier noun for "adherent of democracy" was democratian (1650s).