a. Full of, or characterized by, deceit; serving to mislead or insnare; trickish; fraudulent; cheating; insincere. [ 1913 Webster ]
Harboring foul deceitful thoughts. Shak. [ 1913 Webster ]
adv. With intent to deceive. [ 1913 Webster ]
n. 1. The disposition to deceive; as, a man's deceitfulness may be habitual. [ 1913 Webster ]
2. The quality of being deceitful; as, the deceitfulness of a man's practices. [ 1913 Webster ]
3. Tendency to mislead or deceive. “The deceitfulness of riches.” Matt. xiii. 22. [ 1913 Webster ]