Unreasonable, a. — Webster enters it under “unreasonable”
Not reasonable; irrational; immoderate; exorbitant. -- Un*rea"son*a*ble*ness, n. -- Un*rea"son*a*bly, adv.
Shades of meaning
Fernald lists unreasonableness only as an antonym, under justice.
He lists it without comment; the entries above explain its neighbors.
Synonyms
none given