A nut includes an internal thread and at least two parts, each of the parts having a section of the internal thread which can be pushed onto an external thread in the radial direction. The parts may have connecting elements which interact and permit a relative displacement of the parts in a direction running radially to the axis of the internal thread into a position of use. The connecting elements may have guide surfaces which are inclined at an angle to the plane running radially to the axis of the internal thread and guide the parts in a rotational movement about an axis of rotation running transversely to the axis. A part may have a locking arm with a guide surface only on one side which produces the rotational movement during the displacement of the parts and bears against a complementary guide surface of the other part.