2 Syllables: SU
aerial, Ariel, burial, dreadful, Eccles, Federal, fretful, Hegel, kettle, medal, meddle, metal, mettle, nettle, pebble, pedal, petal, rebel, restful, settle, speckled, spectral, treble
3 Syllables: USU
biennial, Centennial, forgetful, malarial, neglectful, perennial, projectile, respectful, terrestrial, triennial, unsettled
4 Syllables: UUSU
Found 36 words across 3 groupings. Skipped 13 excess words of a similar stem.