2 Syllables: SU
Brussels, bubble, buckle, bustle, chuckle, circle, Colonel, couple, cudgel, double, fertile, funnel, girdle, Herschel, hovel, huddle, hurdle, hurtful, hustle, Journal, kernel, knuckle, Lovell, muddle, muffled, muscle, muzzle, myrtle, puddle, purple, puzzle, rubble, ruffle, Russel, Russell, Russell's, rustle, scuffle, servile, shovel, shuffle, shuttle, smuggle, squirrel, struggle, stubble, subtile, subtle, supple, thermal, trouble, tunnel, turtle, verbal, vernal, Virgil
3 Syllables: USU
commercial, disgruntled, dispersal, diurnal, encircle, eternal, external, fraternal, infernal, internal, maternal, nocturnal, paternal, peripheral, proverbial, rebuttal, redoubled, referral, rehearsal, reversal, unruffled, untroubled
4 Syllables: UUSU
5 Syllables: UUUSU
Found 81 words across 4 groupings. Skipped 45 excess words of a similar stem.