THREAT, a menace or intimidation. At common law the employment of threats or other forms of intimidation to induce a person to enter into a contract will give the right to sue for its recision or avoidance, or to plead the special form of intimidation in answer to any action brought, or to sue for damages occasioned by entering into the contract. (See such headings as COERCION; CONTRACT; EXTORTION, etc.)
In criminal law the sending of threatening letters (or causing them to be received), demanding with menaces and without reasonable cause money or other valuable thing, is a felony. So is the sending a letter threatening to burn or destroy any house, barn or other building or to kill or maun cattle. It is also a felony to threaten to accuse a person of a crime for the purpose of extorting money, or merely to demand money or other property, without having any claim to it, by means of a threat.
Note - this article incorporates content from Encyclopaedia Britannica, Eleventh Edition, (1910-1911)