To hit one of your opponent's "blots" and be unable to follow it up with another "man", thereby leaving your own man exposed.

When you hit your opponent's blot leaving your own blots in danger of a return hit.

Hitting an opponent's checker where you cannot make the point, but have to leave a blot.

To hit a blot of you opponent leaving your blots uncovered and exposed.

To hit an opposing blot and while leaving your own blots in danger of a return hit.

To hit an opposing man at a time when the player's own blots are in danger of a return hit.