What is to combine against (a landlord, tradesman, employer, or other person), to withhold social or business relations from him, and to deter others from holding such relations; to subject to a boycott called?

boycott — To combine against (a landlord, tradesman, employer, or other person), to withhold social or business relations from him, and to deter others from holding such relations; to subject to a boycott. (Webster's 1913.)