If something is objectionable, it is unpleasant and likely to offend people — the sort of thing you could reasonably object to. It often describes behaviour, language, or pictures (‘objectionable content’). The word feels formal, even a little official; complaint letters, school rules, and news reports like it. In ordinary talk, people are more likely to say offensive, nasty, or just not okay. Though actually, objectionable is a shade broader than offensive: something can be objectionable because it is crude, cruel, or simply in very poor taste, not only because it insults a group. A quiet trap lives in the ending: the -able does not mean ‘able to object’. An objectionable person is not someone skilled at complaining; they are someone others have reason to complain about.