Casulties are not deaths, but soldiers which can no longer fight. So when somebody gets badly wounded, they are also a casulty.

Still really horrible though.

There are typically about 5 seriously permanently wounded to 1 dead, and in the case of the Russia, a bit over 2 wounded per 1 dead. The rate is so much lower because many of the soldiers who would end up on the list of wounded end up dying because of the lacking healthcare.

Still: If the million would be dead, there would be 2,5 million seriously permanently injured, and the Russian army would have lost altogether 3,5 million soldiers in dead and wounded. And if 3,5 million had been lost, well, things would look very different.

This proves quite clearly that the number includes also the seriously wounded, and a bit under a third of the number is actual dead.

A casualty is not always a death, it just means that someone is no longer able to fight. Russia has been sending people with a broken arm back to the front at times, so some people may be counted twice in that million. Traditionally one 1/3rd are death, but Russia has often been much higher. I’m not aware of anyone publishing data on how many Russians are dead. 1 million causalities is a large number, and it is the best data we have (at least public data): when other sources publish numbers it is generally close (or we have reason to think the other source is making up numbers). However it doesn’t mean what it appears to.