halving

(navigation) The process of adjusting magnetic compass correctors so as to remove half of the deviation on the opposite cardinal or adjacent intercardinal headings to those on which adjustment was originally made when all deviation was removed; this action is taken to equalize the error on opposite headings.

The cutting away of two wood members at their ends, each to half its thickness; when the two cut surfaces are placed together, a lap joint or half-lap joint is obtained.