The cross between F₁ progeny × either parents is called

The cross between F₁ progeny × either parent is called Back cross.
Backcrossing is a crossing of a hybrid with one of its parents or an individual genetically similar to its parent, to achieve offspring with a genetic identity closer to that of the parent. It is used in horticulture, animal breeding, and production of gene knockout organisms.
Backcrossing may be deliberately employed in animals to transfer a desirable trait in an animal of inferior genetic background to an animal of preferable genetic background.