• (n.) The rod or handle to which the lash of a whip is fastened.
(from the article `petroleum production`) ...a number of small deviations must be made. The borehole, in effect, ends up making a large arc to reach its objective. The traditional tool for ...
a long steel casing that uses an inclined plane to cause the bit to deflect from the original borehole at a slight angle. Whipstocks are sometimes used in controlled directional drilling, in straightening crooked boreholes, and in sidetracking to avoid unretrieved fish. 
Whip'stock` noun The rod or handle to which the lash of a whip is fastened.