Inquiring minds want to know, perhaps because they've been reading about the Petraeus scandal: What's the origin of the word "blackmail"?
The idea of a public official having to resign because moral missteps may have left him vulnerable to blackmail may seem quaint. But so it has played out in the case of the military hero who became entangled with his biographer. Even the pundits who might in principle argue that a public man is entitled to a private life acknowledge that the case of a CIA director is different.
But enough of scandal. Let's get on to the word stuff. Why do we call it "blackmail," anyway?
It's the kind of word literal-minded children glom onto and invent explanations for: "Hmm, it must be something like sending someone a letter in a black envelope."
The metaphor behind blackmail is an "evil agreement." The word goes back to the 1550s. The mail was originally male, a Middle English word meaning rent or tribute, according to the Online Etymology Dictionary. Before male there was an Old English word mal, meaning lawsuit, terms, bargaining, or agreement.
Mal had many word relatives among the Germanic languages, referring to ideas of "meeting" or coming together. Blackmail, you might say, meant making a deal with the devil. The first blackmailers were "freebooting clan chieftains who ran protection rackets against Scottish farmers," the Online Etymology Dictionary explains.
By the 1820s, the term had expanded to refer to any kind of extortion. That more familiar sense of mail ("Has the mail come today?") derives from another root altogether, an Old French word meaning bag or bundle.
It's often interesting to find out what metaphors other languages use to express a certain idea. The German word for blackmail or extortion is Erpressung, a sort of metaphorical "putting the squeeze" on someone. That syllable "press" means the same thing as its counterpart in English, as in "pressure" or even "impress," in the military sense: to take someone against his will for compulsory service, especially aboard a ship. The Royal Navy used to "impress" American sailors all the time – and not favorably; this was one of the issues in the War of 1812.
The French term for blackmail, chantage, is even more picturesque. To blackmail someone is literally to "make him sing" – faire chanter.
Extortion paints another vivid word picture, if you know your Latin roots. The "tort" root means "twist" – as in a tortuous (twisting and winding) mountain road. Extortion involves getting money from someone through threats.
"In modern usage blackmail differs from extortion," writes Maeve Maddox, at Daily Writing Tips, "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."
Before the use of the term blackmail spread beyond the Scottish Highlands, however, there was, back in the 1590s, a term silver mail. It meant rent paid in money (silver), as distinct from in kind (as with a share of a farmer's crop). One imagines that silver mail was probably paid in person, this being before personal checking accounts became widespread; otherwise it would have been possible for a tenant on the verge of arrears to protest, "But the mail is in the mail."