[astrange]

You can certainly get memory abandonment, which is like a leak but for memory that's still referenced and is just never going to be used again.

[tsimionescu]

I will note that in GC literature at least, that is still considered a leak.

In an ideal world, we could have a GC that reclaimed all unused memory, but that turns out to be impossible because of the halting problem. So, we settle for GCs that reclaim only unreachable memory, which is a strict subset of unused memory. Unused reachable memory is a leak.