What is the difference between 'patient' and 'casualty'?

In my experience, the terms 'patient' and 'casualty' tend to be used pretty interchangeably when referring to people in need of medical attention. However, I feel like there's definitely a semantic difference between the two - I just can't quite figure out what it is.

I think any difference might be based on either:

  • where the person is in the chain of care (i.e. a casualty becomes a patient once medical care is provided);
  • the type of issue the person is facing (i.e. 'casualty' would refer to acute trauma or injury whereas a 'patient' would be someone with a chronic condition being treated over a long period of time); or
  • as a relation (i.e. a casualty exists on their own, a patient must be a patient of someone like a doctor).

Or maybe I'm mistaken and there is no functional difference.

The only thing I could find online is this WikiDiff which defines a 'patient' as:

A person or animal who receives treatment from a doctor or other medically educated person.

and 'casualty' as:

A person suffering from injuries or who has been killed due to an accident or through an act of violence.

Which seem to suggest there is a difference, but it seems to straddle all of the differences I proposed (whilst also suggesting that non-human animals can be patients but not casualties).


Your research pretty much captures it:

  • Someone suffering injuries is a casualty (and continues to be so even if they die from their injuries).

  • Someone receiving medical care is a patient (and ceases to be, when they leave that care).

One often leads to the other (i.e the casualty is also a patient), but that's not inevitable. Some casualties die before help can reach them, and many patients are treated for conditions that aren't injuries.


I think you're reading too much when you say that it suggests, "non-human animals can be patients but not casualties". That's not the case - for example, in the cave rescue team of which I'm a member, an animal may well be a casualty and perhaps also become a patient (more often than not, just require extrication and then be happily on its way, none the worse).