The origins of the term black-mail is Scots and the Dictionary of the Scots Language informs us that blackmail is now used in Standard English ‘to mean any kind of payment extorted by intimidation or pressure’.
The term is made up from black plus Scots mail or meal which meant ‘rent, payment in money or kind made under lease’. Black-mail or black-meal, as it was orginally coined, basically meant protection money. In 1771 T. Pennant in A Tour in Scotland observed: “A contribution called the black meal, was raised by several of these plundering chieftains, over a vast extent of country: whoever payed it had their cattle ensured, but those who dared to refuse were sure to suffer.”
Although this was thought by some to be mostly a Borders activity engaged upon by the notorious Borders Reivers the Statistical Account of Scotland records the following information from Perthshire: “Obliging the inhabitants to pay them, Black Meal, as it is called, to save their property from being plundered.”
When law and order eventually put an end to the Scots’ habit of plundering and reiving, the term was still remembered historically as in this example from the Aberdeen Free Press of 9th October 1886: “However, it would have been very easy when leading the horse up a stiff, lonely brae for a band of ruffians to have jumped from behind some bank and demanded black-mail.”
And finally, an example from a scholarly paper quoted in the Falkirk Herald of 6th February 1954: “In a paper entitled “Blackmail in Stirlingshire” Mr Mackenzie said that blackmail was a 17th century practice. The word “blackmail” was originally a Scottish term. It was derived from the Gaelic word, “mail” meaning rent or subsidy, and in the 17th century, blackmail mean the payment of money or other gratuity to thieves for their protection.”