Blackmail
2 of the 7 encyclopedias on this shelf carry an entry for Blackmail. Both are reproduced below, so you can see where they agree and where they differ.
Aiton's Encyclopedia (1910)
a term applied in the days of English and Scotch border warfare to payment made in cattle, corn, or the like, to some chief of robbers for protection from further loss. Scott's Waverley gives a glimpse of the efficient protection afforded by a Fergus McIvor, and the prompt loss of flocks following neglect and refusal to pay blackmail. Farmers in the border country had no choice save that between submission and ruin. In modern usage the term is applied usually to a sum of money extracted from a person through threats of exposure of wrongdoing. "Give me of your flocks or you shall lose" was the message of the Scottish border chieftain. "Give of your money or I'll tell" is the formula of the modern blackmailer. The laws of most states make the levying of blackmail a crime punishable by imprisonment for a term, usually not to exceed five years. 2026 Editor's Note: The word kept its shape but changed its crime. "Mail" was an old Scots word for rent or tribute, so blackmail was literally a black rent paid to raiders. It now covers everything from threats to expose a secret to the digital era's ransomware and "sextortion," in which criminals encrypt or threaten to publish what a victim cannot bear to lose. (Ed: BR 2026-06-16)
Collier's New Encyclopedia (1921)
a certain rate of money, corn, cattle or the like, anciently paid, in the N. of England and in Scotland, to certain men who were allied to robbers, to be protected by them from pillage. In the United States, the word is applied to money extorted from persons under threat of exposure in print for an alleged offense; hush-money.