This noun denotes deceit, deception, or fraudulent misrepresentation. In Jeremiah 14:14, God condemns false prophets who prophesy 'the deceit of their own heart'—that is, self-generated lies they fraudulently attribute to divine revelation. The term emphasizes deliberate deception and falsehood, particularly in the context of false prophecy. The root suggests trickery and misleading, and the usage here highlights the moral culpability of those who claim divine authority for their own fabrications. Deceit here is not mere error but willful fraud, especially dangerous when clothed in religious authority.