The Collaborative International Dictionary of English v.0.48:

Scotch \Scotch\, v. t. [imp. & p. p. Scotched; p. pr. & vb. n.
   Scotching.] [Cf. Prov. E. scote a prop, and Walloon ascot a
   prop, ascoter to prop, F. accoter, also Armor. skoaz the
   shoulder, skoazia to shoulder up, to prop, to support, W.
   ysgwydd a shoulder, ysgwyddo to shoulder. Cf. Scoat.]
   [Written also scoatch, scoat.]
   To shoulder up; to prop or block with a wedge, chock, etc.,
   as a wheel, to prevent its rolling or slipping.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Scotching \Scotch"ing\, n. (Masonry)
   Dressing stone with a pick or pointed instrument.
   [1913 Webster]