2 Syllables: SU
shortening, warbling
3 Syllables: SUU
bordering, forfeiting, formative, fortresses, forwarding, normative, ordering, organised, quartering, shortcoming, torturing
4 Syllables: SUUU
Calvinism, communism, formalism, heathenism, humanism, mechanism, organism, paganism, unionism
4 Syllables: USUU
informative, performances
5 Syllables: USUUU
anachronism, antagonism, determinism, sectarianism
6 Syllables: UUSUUU
microorganisms
7 Syllables: UUUSUUU
utilitarianism

Found 30 words across 7 groupings. Skipped 2 excess words of a similar stem.