Or search: ism
3 Syllables: SUU
dualism, nihilism
4 Syllables: SUUU
fatalism, federalism, feudalism, journalism, naturalism, organism, pluralism, socialism, symbolism, vandalism
5 Syllables: USUUU
colonialism, imperialism, industrialism, materialism, metabolism, paternalism, provincialism
6 Syllables: UUSUUU
microorganisms, sentimentalism
6 Syllables: UUUSUU
individualism

Found 22 words across 5 groupings. Skipped 1 excess word of a similar stem.