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).

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    I wouldn't say that's a subtle difference - a patient is somebody receiving medical care (for any reason - not necessarily because they've been in an accident) while a casualty is somebody who has been injured in an accident or violent incident (whether or not they are receiving medical care). There is an overlap because many patients are also casualties, and vice versa, but the distinction is pretty clear I'd say. Someone being treated for cancer is not a casualty, whereas someone who has been injured but does not receive any treatment is not a patient.
    – JD2000
    Commented Jan 17, 2020 at 10:58
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    In American English, casualty is not used in a medical context. It can be used to refer to injured or dead military personnel, but would very seldom be used to refer to non-military people. (I understand that in British English it is used in a medical context, but cannot draw any fine distinctions as to it.) Commented Jan 17, 2020 at 11:00
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    @Mike: In the U.S., if military actions kill civilians (intentionally or by accident), the deaths are definitely casualties. And if a factory explodes, the injured people can also be called casualties. It's not just for military actions. See this Washington Post article "there have been at least 16 unintended explosions of ammonium nitrate since 1921 that have led to casualties." Commented Jan 17, 2020 at 11:21
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    In terms of subtlety, this is right up there with the difference between "firefighter" and "husband". Some firefighters are husbands, and some husbands are firefighters. But that's not where the commonalities begin; that's where they end.
    – RegDwigнt
    Commented Jan 17, 2020 at 11:48
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    British hospitals used to have a 'Casualty Department'; injured or suddenly sick people were 'rushed into Casualty'; these days it's called "the Accident and Emergency department" (A & E); since 1986 there has been a BBC medisoap called 'Casualty', the longest-running emergency medical drama television series in the world, it seems. At the age of 8 my daughter was adept at predicting which 'patients' would 'croak' as she put it (she is now 40, and a senior nurse). Commented Jan 17, 2020 at 23:08

1 Answer 1


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).

  • In the U.S., we wouldn't use casualty for an automobile accident; just for military actions and for accidents (like fires) that have the potential to injure a large number of people. Commented Jan 18, 2020 at 12:07
  • I didn't know that @Peter. That's certainly different to Britain (all parts that I've been to) where people hurt in road accidents and other relatively small accidents are indeed casualties, but I have much less knowledge of North America, Australia and other English-speaking regions. Commented Jan 20, 2020 at 8:40

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