superimposition

About 0.40 uses per million words.

Meaning

1. noun The process, or the result of superimposing.
2. noun The placing of one image on top of another, especially placing a photograph over some other graphic; an image thus placed.
3. noun The building of ontological categories of a higher level on top of categories of a lower level.

Similar words

superposition layering overlapping overlap overlay super-imposition superseding overmolding overmoulding superinjection

Often followed by

of and is on in upon or by that