Or search: humane, polite, genteel, refined, cultured, civilised, cultivated
3 Syllables: SUU
civilised, civilize, criticized, crystalline, crystallize, Israelite, minimise, minimize, mystified, typified, typifies, visualize
4 Syllables: USUU
epitomized, solidified, uncivilized
5 Syllables: UUSUU
individualized

Found 16 words across 3 groupings. Skipped 4 excess words of a similar stem.