Adjective
missing in action (not comparable)
(chiefly military) The designation for a member of an organization (usually military) with whom contact is lost and whose whereabouts are not known, but whose death is not confirmed.
(by extension) Not present when one is expected to be.
Missing in action were many of the Old Boys stalwarts: Donny Brown, Stefan Cermack, “newbie” Jude Shugar, Mike “Superman” Davis and Matt Johnson on vaccination duty. Source: Internet
The war left 33,742 American soldiers dead, 92,134 wounded, and 80,000 Missing in action (MIA) or Prisoner of war (POW). Source: Internet