Or search: axiom, maxim
4 Syllables: SUUU
aphorisms, barbarism, cataclysm, catechism, mannerisms, naturalism, pauperism, plagiarism, terrorism
5 Syllables: USUUU
anachronism, antagonism, fanaticism, metabolism

Found 13 words across 2 groupings. Skipped 1 excess word of a similar stem.