Ambiguity: an utterance that is capable of two or more denotative or connotative meanings.  New Critics consider intentional ambiguity, in poems, an artistic device, whereas readers of academic prose consider unintentional ambiguity a flaw.  E.g., in King Lear, Edmund the bastard tells Edgar the legitimate son of Kent that his father has been given cause to think Edgar is a traitor to him.  After advising Edgar to "Go armed" (so that in a later scene he can tell Dad that Edgar bore a sword to murder him), Edmund says: "I am no honest man if there be any good meaning towards you" (I.2.169).  Edmund is "no honest man" and for that reason alone, not because of any other conspiracy, there is no "good meaning towards" Edgar.  But Edgar construes the statement to mean Edmund is not "no honest man" (i.e., he is honest) because Edmund warns Edgar that others mean ill towards him.  Edgar is a bad reader of ambiguity, at least at this point in the play.