Complex sentence: Feigned madness a term used in popular culture to describe the assumption of a mental illness for purposes of evasion or deceit, or to divert suspicion, perhaps in advance of an act of revenge.
Split into simpler sentences: Feigned madness a term used in popular culture to describe the assumption of a mental condition or illness by a person for purposes of evasion or deceit. Such an act can also be used to divert suspicion, perhaps in advance of an act of revenge.