Mar·gin n.
 1. A border; edge; brink; verge; as, the margin of a river or lake.
 2. Specifically: The part of a page at the edge left uncovered in writing or printing.
 3. Com. The difference between the cost and the selling price of an article.
 4. Something allowed, or reserved, for that which can not be foreseen or known with certainty.
 5. Brokerage Collateral security deposited with a broker to secure him from loss on contracts entered into by him on behalf of his principial, as in the speculative buying and selling of stocks, wheat, etc.  It is usually less than the full value of the security purchased, in which case it may be qualified by the portion of the full value required to be deposited; as, to buy stocks on 50% margin.
 Margin draft Masonry, a smooth cut margin on the face of hammer-dressed ashlar, adjacent to the joints.
 Margin of a course Arch., that part of a course, as of slates or shingles, which is not covered by the course immediately above it. See 2d Gauge.
 Syn: -- Border; brink; verge; brim; rim.