Or search: handy, reachable, getatable, approachable, availability, accessibility, availableness, comprehensible, comprehendible
2 Syllables: SU
Federal, general
3 Syllables: SUU
bearable, cerebral, clerical, credible, decimal, edible, equable, festival, genital, legible, medical, parable, pedestal, plentiful, preferable, Reginald, seminal, several, skeletal, tenable, terrible, vegetable
4 Syllables: USUU
amenable, chimerical, confessional, congenital, Congressional, detestable, ephemeral, execrable, illegible, impeccable, incredible, ineffable, numerical, polemical, professional, regrettable, unbearable, untenable
5 Syllables: UUSUU
hypothetical, inaccessible, incontestable, indigestible, inexpressible, irrepressible, unforgettable
6 Syllables: UUUSUU
gastrointestinal

Found 50 words across 5 groupings. Skipped 7 excess words of a similar stem.