IOU

American  

Or I.O.U.

1. a written acknowledgment of a debt, especially an informal one consisting only of the letters IOU, the sum owed, and the debtor's signature.

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IOU British  

noun

1. a written promise or reminder to pay a debt

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IOU Cultural  

1. Abbreviation for “I owe you.” An IOU is a written statement of a borrower's obligation to pay a debt.

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Etymology

Origin of IOU

First recorded in 1610–20; representing I owe you

Example Sentences

Essentially, you borrow from the account and create an IOU to yourself.

From MarketWatch • Jan. 14, 2026

Credit is the promise to pay money, an IOU.

From The Wall Street Journal • Dec. 12, 2025

Should a player lose beyond his ability to pay, the others may allow him time to pay off his loss—usually, time until the next game—and he may offer up an IOU.

From The Wall Street Journal • Nov. 6, 2025

Investors see US Treasury securities as one of the safest possible bets, because the bonds - which are kind of like an IOU - are backed by the US government.

From BBC • Jan. 17, 2025

It seemed small of me to be so unhappy when he’d done so much for me, but the IOU had been a bitter surprise.

From "Hattie Big Sky" by Kirby Larson