breakout — If there has been a break-out, someone has escaped from prison.
desertion — the act of deserting or abandoning or the state of being deserted or abandoned
adjective absconding
absent without leave — absent from duty without official permission but with no intention of deserting
on the run — to go quickly by moving the legs more rapidly than at a walk and in such a manner that for an instant in each step all or both feet are off the ground.
awol — If someone in the Armed Forces goes AWOL, they leave their post without the permission of a superior officer. AWOL is an abbreviation for 'absent without leave'.