Plain English Meaning

A spin the pilot cannot get the airplane out of in time, either because the airplane has entered a spin it physically cannot recover from, or because there is not enough altitude left to complete the recovery before hitting the ground.

Full Definition

A spin from which the airplane cannot be returned to controlled flight using normal recovery techniques before ground impact. The condition may result from aerodynamic factors (such as a flat spin where control surfaces lose effectiveness), loading outside the approved center-of-gravity envelope, insufficient altitude to complete recovery, or into a spin the airplane was not designed or certified to recover from.