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

If the IOU isn’t redeemed in good time, the players have a problem.

From The Wall Street Journal • Nov. 6, 2025

A bond is a bit like an IOU that can be traded in the financial markets.

From BBC • Jan. 9, 2025

It was a photocopy of a handwritten note: IOU one Roman praetor.

From "Blood of Olympus" by Rick Riordan