Ambiguity.

With reference to language: the fact or quality of having different possible meanings; capacity for being interpreted in more than one way.

“A double meaning in a single word or phrase. Irony always involves ambiguity.”
John Barton, from his book Playing Shakespeare, Methuen.

Coriolanus: Now good Aufidius,
Were you in my stead, would you have heard
A mother less? Or granted less, Aufidius?
Aufidius: I was moved withal.