uni-, un-

1. Any theory that combines two or more field theories; such as, Maxwell's unification of the field theories of electricity and magnetism by developing the theory of electromagnetism.
2. Specifically, the effort by Einstein and others to unify gravitational force and electromagnetic force with a single set of laws and, more generally, to provide a geometrical interpretation for all physical interactions.

The statement that when an isolated system performs a process after the removal of a series of internal constraints, it will reach a unique state of equilibrium.

A woman who has her first pregnancy.