Scotch is an adjective meaning "of Scotland". The modern usage in Scotland is Scottish or Scots, and the word "Scotch" is only applied to specific products, mostly food or drink, such as Scotch whisky, Scotch pie, Scotch broth, and Scotch eggs. "Scotch" applied to people is widely considered pejorative in Scotland, reflecting old Anglo-Scottish antagonisms, but it is still occasionally used in England and Ireland, though the usage is considered old-fashioned, and is in common use in North America.
The verb to scotch is unrelated to the adjective. It derives from Anglo-French escocher meaning "to notch, nick", from coche, "a notch, groove", extended in English to mean "to put an abrupt end to", with the forms "scotched", "scotching", "scotches". For example: "The prime minister scotched the rumours of her illness by making a public appearance." Also, in the traditional children's game of "hopscotch", known as "peevers" in Scotland, it refers to the lines one hops over.
The adjective or noun Scotch is an early modern English (16th century) contraction of the English word Scottish which was later adopted into the Scots language. It more or less replaced Scottish as the prevailing term in England in the 17th century. The English playwright William Shakespeare used the word Scotch to describe a jig, but always employed the term Scottish when people were the subject.Scots (the modern Scots language form of early Scots Scottis) predominated in Scotland until the 18th century when anglicisation became fashionable and Scotch came to be used in both England and Scotland. A 1788 letter by Robert Burns says in part: "Apropos, is not the Scotch phrase Auld lang syne exceedingly expressive? There is an old song and tune which has often thrilled through my soul. You know I am an enthusiast in old Scotch songs." ("Auld Lang Syne" in The Burns Encyclopedia, at robertburns.org). Burns wrote of himself in 1787, "The appellation of a Scotch Bard, is by far my highest pride; to continue to deserve it is my most exalted ambition." ("National Bard, Scotland's", op. cit.). Thus also Byron: English Bards and Scotch Reviewers ref., 1809).