A oncave depression found at the leading and/or trailing end of a board after it is passed through a planer (thicknesser) or jointer. There are many causes of snipe, including bed height, feed roller pressure/alignment, and the weight of the board itself. Consequently there are numerous ways to prevent snipe. Here’s a great tutorial on preventing planer snipe. Keep in mind that in some cases, no matter what you do, snipe will be a fact of life. In those cases, the only thing you can do is either use another tool to finish the boards or simply cut off the ends of the board after milling.