an informally written, signed acknowledgment of a specified debt, characteristically bearing the letters IOU
Origin of IOUfor I owe you
A promise to pay a debt, especially a signed paper stating the specific amount owed and often bearing the letters IOU.
Origin of IOUFrom the pronunciation of I owe you.
- I owe you.
- Customarily, if you borrow $10 for lunch from a coworker, writing IOU $10 on a yellow sticky note acts as a legal promissory note that you will repay said amount on payday.
From the pronunciation of "I owe you", not the initial letters.