Conˈgressionalist [f.prec. + -ist.] A supporter of a congress; a member of a congressional party. 1891Pall Mall G. 4 Mar. 2/2 (Chili) The Congressionalists are represented as having no troops.1891Times 26 Feb. 5/3 President Balmaceda..has initiated a guerre à mort against the Congressionalists [in Chili].