[n] the tender meat of the loin muscle on each side of the vertebral column
[v] cut obliquely into (a tree) below the main cut and on the side toward which the tree will fall
[v] strike (the ball) in golf, tennis, or hockey obliquely downward so as to give a backspin or elevation to the shot
[v] cut away the underpart of; "undercut a vein of ore"
[v] cut away material from the underside of (an object) so as to leave an overhanging portion in relief
[v] sell cheaper than one's competition