Synonyms and related words :
adrift, amiss, astray, below the mark, beside the mark, beside the question, bootlessly, extraneous, extrinsic, far from it, fruitlessly, immaterial, impertinent, in vain, inadmissible, inapplicable, inapposite, inappropriate, incidental, inconsequent, irrelative, irrelevant, nihil ad rem, nonessential, not at issue, off the subject, out-of-the-way, parenthetical, to no purpose, unessential, vainly