Wounded in action
From Halopedia, the Halo wiki
Wounded in Action, also known as "WIA", is a classification used by the United Nations Space Command to denote service members that have been wounded in a battle.
When Spartans became missing or were killed they were classified as Missing In Action (MIA) or Wounded in Action (WIA) to give the illusion that Spartans never die. It also gave the troops of the UNSC more morale.
It is extremely likely that all Spartans have been wounded in action at some point. [1] One SPARTAN, Cassandra, is considered one of the WIA.
