imposition [impositions](act of imposing, laying on, affixing, enjoining, inflicting, obtruding, and the like) noun [UK: ˌɪm.pə.ˈzɪʃ.n̩] [US: ˌɪm.pə.ˈzɪʃ.n̩]
superposition [superpositions](placing of one thing on top of another) noun [UK: ˌsuː.pə.ˈpəʊz] [US: ˌsuː.pəˈpoʊz]