1. An edge and the area immediately adjacent to it; a border. See synonyms at border.
2. The blank space bordering the written or printed area on a page.
3. A limit in a condition or process, beyond or below which something is no longer possible or acceptable: the margin of reality; has crossed the margin of civilized behavior.
4. An amount allowed beyond what is needed: a small margin of safety. See synonyms at room.
5. A measure, quantity, or degree of difference: a margin of 500 votes.
6. Economics.
   1. The minimum return that an enterprise may earn and still pay for itself.
   2. The difference between the cost and the selling price of securities or commodities.
   3. The difference between the market value of collateral and the face value of a loan.
7. An amount in money, or represented by securities, deposited by a customer with a broker as a provision against loss on transactions made on account.
8. Botany. The border of a leaf.

1. To provide with a margin.
2. To be a margin to; border.
3. To inscribe or enter in the margin of a page.
4. Economics.
   1. To add margin to: margin up a brokerage account.
   2. To deposit margin for: margin a transaction.
   3. To buy or hold (securities) by depositing or adding to a margin.

[Middle English, from Old French, from Latin margō, margin-.]

The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved.