Deligne–Mumford stack
in algebraic geometry, an algebraic stack with an étale atlas
moduli stack of elliptic curves
smooth separated Deligne–Mumford stack of finite type over Spec ℤ, describing elliptic curves of a specified genus g with a specified number n of marked points, which fails to be a scheme due to nontrivial automorphisms of elliptic curves
algebraic space
generalization of a scheme; an étale equivalence relation on a scheme; a sheaf of sets on the big étale site with representable diagonal morphism and a surjective étale morphism from a scheme