Or search: arc, lap, orb, disc, disk, loop, oval, pack, rope, orbit, roach, seats, troll, roofy, rophy
2 Syllables: SU
circle, Colonel, fertile, girdle, Herschel, hurdle, hurtful, Journal, kernel, myrtle, purple, servile, 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 38 words across 4 groupings. Skipped 15 excess words of a similar stem.