Or search: dullness, hardness, callosity, insensitivity, insensibility
2 Syllables: SU
cabinets
3 Syllables: SUU
amorous, animates, aqueducts, avarice, clamorous, fatuous, glamorous, graduates, Lazarus, naturalist, ravenous, satirist, valorous
4 Syllables: USUU
analogous, antagonist, calamitous, gelatinous, magnanimous, paralysis, protagonist, unanimous
5 Syllables: UUSUU
pusillanimous, undergraduates
6 Syllables: UUUSUU
psychoanalysis

Found 25 words across 5 groupings. Skipped 2 excess words of a similar stem.