Definition of "AWOL"

(originally military) Absent without official leave (permission).

(military) Absence without proper authority from the properly appointed place of duty, or from unit, organization, or other place of duty at which one is required to be at the time prescribed.

(military) A person who holds AWOL status.

(by extension) Somebody who is absent without permission.  examples

(figuratively) Someone or something missing.  examples