SET-OFF, in law, a statutory defence to the whole or to a portion of' a plaintiff's claim. It had no existence under the English common law, being created by 2 Geo. II. c. 22 for the relief of insolvent debtors. Such a defence could be pleaded only in respect of mutual debts of a definite character, and did not apply to cases in which damages were claimed, nor to equitable claims or demands. By the rules of the Supreme Court (O. XIX. r. 3) a defendant in an action may set off or set up any right or claim by way of counterclaim against the claims of a plaintiff, and such set-off or counterclaim has the same effect as a statement of claim in a cross-action. (See Pleading.)
In architecture, the term set-off is given to the horizontal line shown where a wall is reduced in thickness, and consequently the part of the thicker portion appears projecting before the thinner. In plinths this is generally simply chambered. In other' parts of work the set-off is generally concealed by a projecting string. Where, as in parapets, the upper part projects before the lower, the break is generally hid by a corbel table. The portions of buttress caps which recede one behind another are also called sets-off.