conˈgressionist [f. congression + -ist. Cf.prec.] A member or supporter of a congress. 1889Pall Mall G. 24 Jan. 6/2 You speak of agitators. Do you refer to congressionists?1889N. Digby ibid. 27 Feb. 2/3 To favour me with the names of the Congressionists who received Russian gold.