This is a little question that around out of [this] (https://np.reddit.com/r/ShitWehraboosSay/comments/6l7vdp/western_front_is_moron_brigade_turkey_shoot_the/djs2b5t/?st=j4qoxyv8&sh=523c2e0a) thread on /r/ShitWehraboosSay. I have been under the impression that a casualty is any soldier unavailable for duty, mostly due to my long-held habit of reading Wikipedia articles, where the convention is to list POWs as casualties of battles and wars. /u/Ophichius is under the impression that casualties only include soldiers who have been wounded (presumably also people who have been wounded to death). We have decided to let this sub arbitrate.
What is the consensus on this among historians? Among military personnel? Among journalists? Among other relevant categories that I missed?
Just to clarify, my understanding of the topic is that KIA/WIA are always counted as casualties, some militaries have counted those with battlefield illness (trench foot, etc.) as casualties, and POWs are typically categorized separately.
However, this is just my understanding gleaned from a layperson's reading of the literature, and not any sort of formal training. Hence why we're appealing to the good folk of /r/AskHistorians.