Atomic Model

A model in which every finite tuple realizes an atomic (principal) type over the empty set; equivalently, every finite tuple has a complete formula isolating its type, so types over ∅ are determined by single formulas.

A countable model (more generally, a model in a given size) is atomic if every finite tuple in the model realizes a type that is isolated by a single formula; equivalently the complete types realized in the model are isolated points in the relevant type spaces.