sell someone down the river
idiom (informal)

- to put someone in a difficult or dangerous situation by not acting as you had promised to act, usually in order to win an advantage for yourself

- to deceive or betray

The Cambridge Dictionary / Collins Dictionary

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PHRASE ORIGIN

Probably from the practice in the U.S., prior to the American Civil War, of trading in slaves who were transported via the Mississippi River:

Mark Twain (1885), chapter 42, in Huckleberry Finn: “He ain't no slave... Old Miss Watson died two months ago, and she was ashamed she ever was going to sell him down the river, and said so; and she set him free in her will."

This expression, dating from the mid-1800s, alludes to slaves being sold down the Mississippi River to work as labourers on cotton plantations. Its figurative use dates from the late 1800s.

USAGE CONTROVERSY !

Although you’ll often hear or read the phrase ‘sold down the river’, the BBC has reportedly banned its sports presenters from using it because it reinforces “racist” attitudes. Other banned phrases are 'blacklisted', 'black mark’, and 'whiter than white'.

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THE ANTIDOTE TO BETRAYAL

- Synonyms for loyalty:

amigo, amigos for life, attachment, bestie, BFF (Best Friends Forever), birds of a feather, blood brother, boon companion, bosom buddy, brother from another mother, brotherhood, buddy, camaraderie, chum, chumminess, chummy, close-knit, companion, comrade, comrade-in-arms, confidant(e), copilots, dearest friend, fast friends, fellowship, fellow traveler, friendliness, friends forever, have each other's backs, heart-to-heart, home team, inseparable(s), intimacy, kindred (spirit), kinship, lifemate, like-mindedness, main man, mate, matey, my people, old pals, on the same wavelength, pal, partner-in-crime, right-hand man, running buddies, shoulder to cry on, side by side, sidekick, sisterhood, soulmate, soul sister, squad, sworn friend, teammate, the yin to my yang, thick as thieves, through thick and thin, tight bond, true blue, trueheartedness, true mate, trust, two peas in a pod, unswerving loyalty, wingman

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