''In this Part— (1) “association” means any combination or body of perssns, whether the same be known by any distinctive name or not; and (2) “ unlawful association ” means an association— (n) which encourages or aids persons to commit acts of violence or intimidation or of which the members h bilingually commit such acts, or (b) which Ins been declared to be unlawful by the President of the Union under the powers hereby conferred...''