Perfidiousness
Part of speech: noun
Definition: Unfaithfulness; deceitfulness; perfidy.
Treachery
Part of speech: noun
Definition: Deliberate, often calculated, disregard for trust or faith.The act of violating the confidence of another, usually for personal gain.Treason.
Example sentence: While the form of treachery varies slightly from case to case, liberals always manage to take the position that most undermines American security.