closed immersion
morphism of schemes f: X → Y such that the induced morphism from the structure sheaf of Y to its pullback onto Y is surjective; equivalently, one that can be defined by a quasicoherent sheaf of ideals
en-GB/ˈkləʊzd ɪˈmɜːʃn/
en-US/ˈkloʊzd ˌɪˈmɝʒən/