Adjectives

(s)unsuitablenot meant or adapted for a particular purpose“a solvent unsuitable for use on wood surfaces”
(s)inapplicable, unsuitablenot capable of being applied“rules inapplicable to day students”
(s)unsuitablenot conducive to good moral development“the movie is unsuitable for children”
(s)undesirable, unsuitablenot worthy of being chosen (especially as a spouse)