2 Syllables: SU
3 Syllables: SUU
bearable, cerebral, chemical, clerical, credible, decimal, edible, equable, ethical, festival, genital, legible, medical, metrical, parable, pedestal, plentiful, preferable, Reginald, seminal, several, skeletal, spherical, tenable, terrible, variable, vesicles
4 Syllables: USUU
accessible, amenable, chimerical, confessional, congenital, Congressional, detestable, ephemeral, execrable, heretical, hysterical, illegible, impeccable, incredible, indelible, ineffable, intestinal, invariable, poetical, polemical, professional, referable, regrettable, symmetrical, unbearable, untenable
5 Syllables: UUSUU
academical, alphabetical, antithetical, arithmetical, asymmetrical, biochemical, ecumenical, evangelical, geometrical, hypothetical, imperturbable, inaccessible, incontestable, indigestible, inexpressible, irrepressible, theoretical, unforgettable
6 Syllables: UUUSUU
Found 75 words across 5 groupings. Skipped 8 excess words of a similar stem.