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

While that may be technically correct, the £1.68bn value is based on an IOU that is ultimately backed up by Severn Trent Water itself.

From BBC • Dec. 9, 2024

Since I can’t afford to buy Dad that engraved picture frame until Mrs. Gilbert can afford to pay me, I decide to give him a handmade IOU.

From "Shine!" by J.J. and Chris Grabenstein