Lock for a door or a window, wherein the lock has a lock housing, in which a lock mechanism, preferably with a lock bolt and/or lock latch, is mounted, wherein the lock mechanism - has at least one rotation element, which is rotatably mounted in a rotation bearing in the lock housing, - has at least one slide element (8a, 8i), which is linearly shiftably mounted in a slide bearing in the lock housing, wherein the at least one slide element (8a, 8i) is supplied by a spring (6a, 6i) and, on one side, the spring (6a, 6i) is supported on the at least one slide element (8a, 8i) and, on the other side, is supported indirectly or directly on the lock housing, preferably on the slide bearing (80a, 80i) of the slide element (8a, 8i), and - has a transmission device (9a, 9i), which is connected to the at least one rotation element (4a, 4i) and to the at least one slide element (8a, 8i), and the rotational movement of the at least one rotation element (4a, 4a) transfers to the at least one slide element (8a, 8i) and/or the movement of the at least one slide element (8a, 8i) transfers to the at least one rotation element (4a, 4i), wherein the spring (6a, 6i) supplies the rotation element from an actuated position into a base position by means of the transmission device (9a, 9i), wherein the transmission device has at least one conrod (9a, 9i), and the at least one conrod (9a, 9i) of the transmission device is hinged with its one end on the slide element (8a, 8i) and is hinged with its other end on the rotation element (4a, 4i) eccentrically in relation to the rotation axis of the rotation element, characterised in that the at least one conrod (9a, 9i) of the transmission device is formed as a circular sectional or arcuate or trapezoidal body in such a way that the outer contour of the rotation element is recessed. - has at least one rotation element, which is rotatably mounted in a rotation bearing in the lock housing, - has at least one slide element (8a, 8i), which is linearly shiftably mounted in a slide bearing in the lock housing, wherein the at least one slide element (8a, 8i) is supplied by a spring (6a, 6i) and, on one side, the spring (6a, 6i) is supported on the at least one slide element (8a, 8i) and, on the other side, is supported indirectly or directly on the lock housing, preferably on the slide bearing (80a, 80i) of the slide element (8a, 8i), and - has a transmission device (9a, 9i), which is connected to the at least one rotation element (4a, 4i) and to the at least one slide element (8a, 8i), and the rotational movement of the at least one rotation element (4a, 4a) transfers to the at least one slide element (8a, 8i) and/or the movement of the at least one slide element (8a, 8i) transfers to the at least one rotation element (4a, 4i), wherein the spring (6a, 6i) supplies the rotation element from an actuated position into a base position by means of the transmission device (9a, 9i), wherein the transmission device has at least one conrod (9a, 9i), and the at least one conrod (9a, 9i) of the transmission device is hinged with its one end on the slide element (8a, 8i) and is hinged with its other end on the rotation element (4a, 4i) eccentrically in relation to the rotation axis of the rotation element, characterised in that the at least one conrod (9a, 9i) of the transmission device is formed as a circular sectional or arcuate or trapezoidal body in such a way that the outer contour of the rotation element is recessed.