Or search: neutral, objective, nonpersonal, nonsubjective
3 Syllables: SUU
cervical, permeable, purposeful, terminal, versatile, vertebral, virginal, workable, worshipful
4 Syllables: USUU
convertible, discernible, observable, reversible, unworkable
5 Syllables: UUSUU
interpersonal, irreversible

Found 16 words across 3 groupings. Skipped 1 excess word of a similar stem.