squash tennis, game played on a four-walled court, similar in dimensions to the court on which squash racquets is played. The two games, however, differ in equipment, rules, and play. The squash tennis ball, the size of a lawn tennis ball, is larger and livelier than the squash racquets ball, and the squash tennis racket is the shape of a tennis racket but is smaller. The rules differ especially concerning the service; e.g., in squash tennis a ball may not carom off the side walls before hitting the front wall on the service, the service must bounce in front of the floor service line, volleying (i.e., returning the ball before it hits the floor) is forbidden in returning the service, and only the server may score a point. Squash tennis developed during the 1880s when some Americans began to play squash racquets with a modified tennis ball in order to speed up play.