Or search: intrinsic, inviolable, infrangible, indefeasible, unassignable, unforfeitable, nontransferable
3 Syllables: SUU
fashionable, reasonable
4 Syllables: SUUU
pardonable, questionable, seasonable, treasonable
5 Syllables: USUUU
abominable, companionable, determinable, imaginable, impressionable, interminable, objectionable, unfashionable, unpardonable, unquestionable, unseasonable
6 Syllables: UUSUUU
unexceptionable

Found 18 words across 4 groupings.