Pseudoelementary class

The term "pseudoelementary class" is primarily used in the context of model theory, particularly in relation to certain classes of structures. In model theory, a pseudoelementary class is a generalization of an elementary class that is defined based on a more relaxed set of criteria for the structures it includes. Specifically, an elementary class of structures is one that can be characterized by a set of first-order sentences in a logical language.