Source : Webster's Revised Unabridged Dictionary (1913)

Set-off \Set"-off`\, n. [Set + off.]
   1. That which is set off against another thing; an offset.

            I do not contemplate such a heroine as a set-off to
            the many sins imputed to me as committed against
            woman.                                --D. Jerrold.

   2. That which is used to improve the appearance of anything;
      a decoration; an ornament.

   3. (Law) A counterclaim; a cross debt or demand; a distinct
      claim filed or set up by the defendant against the
      plaintiff's demand.

   Note: Set-off differs from recoupment, as the latter
         generally grows out of the same matter or contract with
         the plaintiff's claim, while the former grows out of
         distinct matter, and does not of itself deny the
         justice of the plaintiff's demand. Offset is sometimes
         improperly used for the legal term set-off. See
         {Recoupment}.

   4. (Arch.) Same as {Offset}, n., 4.

   5. (Print.) See {Offset}, 7.

   Syn: {Set-off}, {Offset}.

   Usage: Offset originally denoted that which branches off or
          projects, as a shoot from a tree, but the term has
          long been used in America in the sense of set-off.
          This use is beginning to obtain in England; though
          Macaulay uses set-off, and so, perhaps, do a majority
          of English writers.