Mesosystem

undefined:

A mesosystem is a group in a system that is larger or more distinct than a sidesystem but too small or not distinct enough to be a hemisystem. Mesosystems may contain sidesystems, subsystems, sparsystems, or any other grouping.

The term comes from the Ancient Greek adjective for "middle, between, amidst".

Related terms
As a type of sisasystem, the term mesosystem is related to other sisasystem terms. While most commonly within a hemisystem, subplex, or larger/more separate grouping, mesosystems can be anywhere in a system's structure.

Metaregna are similar to mesosystems, being groupings of sidesystems, but are decidedly a "looser" form or type of grouping.