"Indefinitely" applies to every war ever fought.
No. That's still a misuse of the term*. A prisoner of war can only be held until the end of major hostilities. This is not indefinite detention. Indefinite means with no definition of conditions for release. No one can be held indefinitely.
Further, if you're talking about someone accused of a crime in connection with the 9-11 attacks, those detainees have the right to writs of
habeas corpus (must be charged or released) or its equivalent.
*ETA: At the very least, you're equivocating when you pretend that other people are using "indefinitely" the way you are.
ETA again: Article 118 of the Geneva Convention in question, makes it clear that the definition of conditions for release must be stipulated (one way or another) and communicated to the detainee. There's nothing open-ended about it.
Article 118
Prisoners of war shall be released and repatriated without delay after the cessation of active hostilities.
In the absence of stipulations to the above effect in any agreement concluded between the Parties to the conflict with a view to the cessation of hostilities, or failing any such agreement, each of the Detaining Powers shall itself establish and execute without delay a plan of repatriation in conformity with the principle laid down in the foregoing paragraph.
In either case, the measures adopted shall be brought to the knowledge of the prisoners of war.
Since conditions for release must be defined, it's not correct to say they're being held indefinitely.
And again, since terrorism is a crime, anyone accused of terrorist activity gets the rights of the accused (
habeas corpus or equivalent, notably), and the "War on Terrorism" isn't about prisoners of war anyway. However, if one attempts to construe it that way, I think it's obvious that the elimination of terrorist crimes cannot be said to be the conditions for release (cessation of active hostilities) because such a condition is unattainable.
I think attempting to equate the war in Afghanistan with the "War on Terrorism" is unreasonable. One is a war in the sense of the Geneva Conventions' rules for the treatment of prisoners of war, and the other is not.