contre-porte

Etymology
From. From being a door counter/opposite to the primary door, the anti-facing door.

Noun

 * 1) a secondary door placed inside or outside of the primary door
 * 2) a storm door an exterior door placed outside the primary door to improve weatherproofing

Coordinate terms

 * screen door
 * / /  aluminum door / aluminium door
 * / /  aluminum door / aluminium door