extraneous(not belonging to, or dependent upon, a thing) adjective [UK: ɪk.ˈstreɪ.nɪəs] [US: ek.ˈstreɪ.niəs]
irrelevant(not related, not applicable, unimportant, not connected) adjective [UK: ɪ.ˈre.lə.vənt] [US: ɪ.ˈre.lə.vənt]Watching television is like studying, but perhaps about irrelevancies. = Ver la televisión es como estudiar, pero quizá sobre cosas irrelevantes.
moot(having no practical importance) adjective [UK: muːt] [US: ˈmuːt]
pointless(having no prominent or important feature) adjective [UK: ˈpɔɪnt.lɪs] [US: ˌpɔɪnt.ləs]