train transient

Transience means passing with time or is the state of being brief and short-lived. Something which has the property of transience is said to be transient, or often simply in a transient or transient state.

Transient State
The exact point at which a device changes modes, for example,from transmit to receive or from 0 to 1.

A system is said to be in transient state when a process variable has been changed and the system has not yet reached steady-state.

The transient response is not necessarily tied to "on/off" events but to any event that affects the equilibrium of the system.