A vector that gives a measure of the size and direction of a dislocation in a crystal. It is defined in terms of a circuit inside a crystal. In the case of a perfect crystal the circuit closes. If there is a dislocation inside the circuit it fails to close, with the Burgers vector being given by the measure of the failure to close. It was introduced by the Dutch physicist Johannes Martinus Burgers 1895–1981) in 1939.