1. adjective If you describe a question as unanswerable, you mean that it has no possible answer or that a particular person cannot possibly answer it. ⇒ They would ask their mother unanswerable questions. 2. adjective If you describe a case or argument as unanswerable, you think that it is obviously true or correct and that nobody could disagree with it. ⇒ He actually became convinced that the nurses had an unanswerable case. ⇒ The argument for recruiting McGregor was unanswerable.
COBUILD Advanced English Dictionary. Copyright © Harper Collins Publishers