Q From Evan Parry, New Zealand : In conversation about a culinary celebration, my friend used the expression polish off, thus: “I polished off the leftover food next morning”. While its meaning in context is generally understood, where and how did the expression originate?
A It does indeed often appear in connection with food, the key idea being that of consuming it completely and probably quickly:
I could easily polish off a packet of biscuits throughout the afternoon, before my dinner of cheesy pasta with buttered bread.
The Sun (London), 15 May 2016.
though it can be used in a variety of other situations, implying the rapid completion of some activity or the subjugation of some adversary:
Freshman Matt McFadden returned the opening kickoff 36 yards and senior Kyle Wigley polished off the drive with a two-yard run into the end zone.
Gettysburg Times (Pennsylvania), 14 Nov. 2015.
He’ll limp to the election; cross the line sadly weakened; and then, in due course, be polished off by another thrusting contender who better understands the political process and can command a majority of the party.
The Age (Melbourne), 24 May 2016.
The idiom has been around since at least the early nineteenth century. Its initial examples were all in the more general sense, extending to getting rid of something, or even to destroy or kill. The application to food seems to have come along a little later in the century, sometimes being simplified to polish without the off. But in his Classical Dictionary of the Vulgar Tongue of 1785 Francis Grose mentions to polish a bone, meaning to eat a meal, so perhaps the food sense really did come first.
The idea here is presumably that of clearing the dish by eating everything on it so thoroughly that it ends up appearing polished. This modern work makes it explicit:
He knew that it was polite to leave a little something on your plate when you finished, but this evening he decided to throw etiquette aside and polished his plate to a shine.
Adam, by Richard Allen Stotts, 2001.
The earliest usages of polish off, however, focus on defeating somebody. Some slang dictionaries expressly say that the first context for the idiom was “pugilistic”, that is, linked to bare-knuckle fist fighting:
Bob had his coat off at once — he stood up to the Banbury man for three minutes, and polished him off in four rounds easy.
Vanity Fair, by William Makepeace Thackeray, 1847.
It may be that a slightly different idea is behind this meaning. Since polishing is the last job to be done to complete a piece of work such as making an item of furniture, to polish off an opponent is to finish him, to defeat him utterly.