• noun:   a cut made underneath to remove material
• noun:   a notch cut in the trunk of tree in order to determine the direction of its fall
• noun:   the material removed by a cut made underneath
• noun:   (sports) a stroke that puts reverse spin on the ball
• noun:   the tender meat of the loin muscle on each side of the vertebral column
• verb:   cut obliquely into (a tree) below the main cut and on the side toward which the tree will fall
• verb:   strike (the ball) in golf, tennis, or hockey obliquely downward so as to give a backspin or elevation to the shot
• verb:   cut away the underpart of

  Example: "Undercut a vein of ore"

• verb:   cut away material from the underside of (an object) so as to leave an overhanging portion in relief
• verb:   sell cheaper than one's competition

Related words...