Or search: unfree, fawning, slavish, slavelike, obsequious, subservient, sycophantic, bootlicking
2 Syllables: SU
circle, Colonel, fertile, girdle, Herschel, hurdle, hurtful, Journal, kernel, myrtle, purple, squirrel, thermal, turtle, verbal, vernal, Virgil
3 Syllables: USU
commercial, dispersal, diurnal, encircle, eternal, external, fraternal, industrial, infernal, internal, maternal, nocturnal, paternal, proverbial, referral, rehearsal, reversal
4 Syllables: UUSU
controversial, universal
5 Syllables: UUUSU
entrepreneurial

Found 37 words across 4 groupings. Skipped 16 excess words of a similar stem.