Two legal terms similar in meaning are extortion and blackmail. Both involve the practice of getting money from victims with threats.
Extortion comes from Latin extortionem, “a twisting out.” The crime involves obtaining something, usually money, from a person by force or wrongful use of authority or power.
A former city of Miami police officer charged with extortion is accused of writing a false police report and protecting purportedly stolen property in exchange for payments, authorities said.
The term blackmail originated in reference to the “protection money” demanded by clan chieftains from Scottish farmers in exchange for leaving them alone. The word has always conjured up the image in my mind of a black envelope containing a threat and a demand for money. In fact, the “mail” part of blackmail derives from Middle English male, “rent, tribute.” Old English mal meant “lawsuit, terms, bargaining, agreement.” The “black” of blackmail refers to association of the color black with evil.
In modern usage blackmail differs from extortion in that the money or other valuable object or act is not extorted by threat of direct bodily harm, but by the threat of revealing something presumed to be injurious to the victim.
A CBS News producer who blackmailed David Letterman for $2 million [about extra-marital affairs] is going away for six months
This difference in meaning between blackmail and extortion obtains in American English, but in cruising the web to prepare this post, I discovered evidence that the original use of blackmail to mean extortion by threat of physical harm may still be current in British English:
Blackmailer threatened to nail victim’s hand to floor: A BLOCK paver who threatened to nail a man’s hand to the floor if he did not get the £1,000 owed to him has been jailed for three years.
A BLACKMAILER tried to extort £40,000 from a businessman by threatening to kill him and dismember his body.