0 abbreviation for missing in action: used for saying that a member of the armed forces has not returned from fighting in a war but is not known for certain to be dead :
1 abbreviation for missing in action: a member of the armed forces who has not returned from fighting in a war but is not known for certain to be dead:
The agency is responsible for tracking down MIAs.
Unrecorded deaths in prison camps contributed to the high number of MIAs at that time.