Exomemories (or exomems) is a term that originated in the plural community as a catch-all term for memories that did not occur in this universe/life. It is derived from the term exotrauma, and while all exotrauma is exomemories, not all exomemories are exotrauma.
The term can also be used to describe memories that are "pre-system" memories by a system member in a system that uses a psychological viewpoint about their system, such as a purely neurogenic system, as an alternative to pseudomemories. A system using the term does not inherently imply that they are spirigenic or have a spiritual component to their plurality, but many who use the term do have such a component to their plurality.