Or search: sane, valid, logical, tenable, fairish, rational, sensible, commonsense, levelheaded, commonsensical, commonsensible
3 Syllables: SUU
fashionable, feasible, peaceable, readable
3 Syllables: UUS
agreeable, foreseeable
4 Syllables: SUUU
irritable, pardonable, questionable, seasonable, treasonable
4 Syllables: USUU
amenable, appreciable, conceivable, unreasonable, unspeakable
4 Syllables: UUUS
disagreeable
5 Syllables: USUUU
abominable, companionable, determinable, imaginable, impressionable, inalienable, interminable, objectionable, unfashionable, unpardonable, unquestionable, unseasonable
5 Syllables: UUSUU
inconceivable, irremediable, irretrievable, unbelievable, unimpeachable
6 Syllables: UUSUUU
unexceptionable

Found 35 words across 8 groupings.