A terminal socket for an electrical terminal system configured to be mated with a terminal pin along a mating direction includes a wiring portion and an electrical contacting portion having a main body with a hollow space for receiving the mating terminal pin, wherein the main body has an external shape not showing a twofold rotational symmetry in a plane perpendicular to the mating direction, and in that the hollow space does not show a twofold rotational symmetry in said plane, or in that the main body has an external shape comprising a triangularly shaped portion, in particular triangularly shaped in a plane perpendicular to the mating direction. A terminal system uses the terminal socket and a terminal pin and a connector uses the terminal sockets in a housing.