Source : Webster's Revised Unabridged Dictionary (1913)

Margin \Mar"gin\, n. [OE. margine, margent, L. margo, ginis. Cf.
   {March} a border, {Marge}.]
   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. --N. Biddle.

   {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.