Or search: undue, mindless, illogical, senseless, untenable, unlogical, inordinate, irrational, immoderate, unjustified, indefensible, reasonableness, counterintuitive
3 Syllables: SUU
feasible, peaceable, readable, reasonable
3 Syllables: UUS
agreeable, foreseeable
4 Syllables: USUU
amenable, appreciable, conceivable, unspeakable
4 Syllables: UUUS
disagreeable
5 Syllables: UUSUU
inconceivable, irremediable, irretrievable, unbelievable, unimpeachable

Found 16 words across 5 groupings.