Or search: obligation, obligatory, requirement, precondition
2 Syllables: SU
Everett
3 Syllables: SUU
baronet, deficit, definite, delegate, delicate, desolate, estimate, etiquette, exquisite, Federalist, Methodist, prejudiced, requisite
4 Syllables: USUU
confederate, Connecticut, degenerate, indefinite, inveterate, prerequisites
5 Syllables: UUSUU
underestimate

Found 21 words across 4 groupings. Skipped 6 excess words of a similar stem.