Connector

1. A connector, comprising:

a housing having opposite front and rear ends, the front end being configured to be connected to a mating housing;

the housing having opposite upper and lower surfaces and opposite side walls constituting an outer surface of the housing, the side walls being joined to the upper and lower surfaces via upper and lower corners respectively; and

upper and lower arched steps provided at plural positions in a front-rear direction so that each of the upper and lower arched steps extends from the respective side wall to the upper and lower corners, the steps including forward-most steps that are smaller in a vertical direction and a lateral direction than each of the steps at more rearward positions, and each of the steps rearward of the forward-most steps being larger in the vertical and lateral directions than the steps at more forward positions.

2. The connector of claim 1 , wherein cavities extend through the housing in the front-rear direction for accommodating terminal fittings, and the housing includes lightening portions defining openings extending forward in the rear surface at positions outward of the cavities and inward of the side walls and the corners.

3. The connector of claim 1 , wherein each of the side walls includes a recess constricted into a concave surface between the upper and lower steps.

4. The connector of claim 3 , wherein each of the recesses is continuous at a constant height in the front-rear direction on the side wall ( 56 ).

5. The connector of claim 1 , wherein the housing includes a lock arm for holding the mating housing in a connected state and protection walls located on both sides of the lock arm, the lock arm and the protection walls being provided on one of the upper or lower surfaces, and the steps are coupled integrally to the protection walls or arranged in proximity to the protection walls.