Complex sentence: "Breaking the fourth wall" is any instance in which this performance convention, having been adopted more generally in the drama, is violated, this can be through either directly referencing the audience or the work they are in or referencing their fictionality.
Split into simpler sentences: Breaking the fourth wall is any instance in which this performance convention, having been adopted more generally in the drama, is violated. This can be done through either directly referencing the audience or the work they are in, or referencing their fictionality.