2 Syllables: SU
beetle, Cecil, cheerful, Cyril, diesel, eagle, easel, equal, equalled, equals, evil, fearful, febrile, Federal, feeble, fetal, general, legal, lethal, measles, needle, penal, people, regal, renal, sequel, siecle, steeple, tearful, venal, virile, weasel
3 Syllables: SUU
bearable, clerical, credible, decimal, edible, equable, festival, genital, legible, medical, parable, pedestal, plentiful, preferable, Reginald, seminal, several, skeletal, tenable, terrible, variable
3 Syllables: USU
adrenal, cathedral, coeval, enfeebled, funereal, illegal, medieval, primeval, retrieval, unequal, unequalled, upheaval
4 Syllables: USUU
accessible, amenable, chimerical, confessional, congenital, Congressional, detestable, ephemeral, execrable, illegible, impeccable, incredible, ineffable, invariable, numerical, polemical, professional, referable, regrettable, unbearable, untenable
4 Syllables: UUSU
5 Syllables: UUSUU
hypothetical, imperturbable, inaccessible, incontestable, indigestible, inexpressible, irrepressible, unforgettable
6 Syllables: UUUSUU
Found 98 words across 7 groupings. Skipped 19 excess words of a similar stem.