Or search: untimely, inopportune
3 Syllables: SUU
fashionable, reasonable
4 Syllables: SUUU
irritable, pardonable, questionable, seasonable, treasonable
5 Syllables: USUUU
abominable, companionable, determinable, imaginable, impressionable, inalienable, interminable, objectionable, unfashionable, unpardonable, unquestionable
6 Syllables: UUSUUU
unexceptionable

Found 19 words across 4 groupings.