Blending

Blending is an operation where two or more polytopes are overlaid such that some pairs of elements coincide in space. Coincident pairs of elements that end up on the inside of the resultant polytope (usually including the highest-dimensional pairs of elements) are removed entirely, while coincident pairs of elements that end up on the outside are each merged into one element.

In the context of the Johnson solids, a similar operation is referred to as "augmenting."