Opportunism rhymes with:
abolitionism, agrarianism, americanism, anachronism, antagonism, arianism, authoritarianism, buchananism, chauvinism, communism, confucianism, creationism, darwinism, determinism, egalitarianism, expansionism, expressionism, feminism, hedonism, hellenism, hooliganism, humanism, illusionism, impressionism, interventionism, isolationism, jansenism, leninism, mechanism, microorganism, modernism, obstructionism, organism, paganism, perfectionism, peronism, protectionism, puritanism, reaganism, republicanism, revisionism, satanism, sectarianism, stalinism, tokenism, totalitarianism, unionism, zionism