A more thorough explanation:

An enemy combatant is a person who fights against the United States during a time of war or conflict. This term was created by President George W. Bush's administration to describe people suspected of supporting or participating in terrorist activities against the United States.

Enemy combatants are detained by the U.S. military without charge and for an indefinite amount of time. They are not given the same rights and protections as prisoners of war under the Third Geneva Convention of 1949. The U.S. military has used this term to detain members of Al-Qaida and Taliban fighters.

For example, after the 9/11 attacks, many suspected terrorists were detained as enemy combatants and sent to Guantanamo Bay prison. They were held there without charge and subject to interrogation techniques that were considered torture.

The status of enemy combatants has been controversial because it raises questions about whether they are entitled to the same protections as prisoners of war and whether they have the right to challenge their imprisonment in U.S. courts. In 2004, the U.S. Supreme Court ruled that enemy combatants have the right to challenge their imprisonment through habeas corpus petitions filed in U.S. courts. In 2008, the Supreme Court confirmed this right in Boumediene v. Bush.

In 2009, the Obama administration ruled that detainees in Guantanamo would no longer be designated as enemy combatants. However, they would still be held indefinitely without charge.