Auxetics are materials that have a negative Poisson's ratio. When stretched, they become thicker perpendicular to the applied force. Auxetic materials can be created from particular structures of macroscopic matter. Such materials are expected to have mechanical properties such as high energy absorption and fracture resistance. Auxetics may be useful in applications such as body armor, packing material, knee and elbow pads, robust shock absorbing material, and sponge mops. The term auxetic derives from a Greek word which means "that which tends to increase", This terminology was coined by Ken Evans of the University of Exeter.