Has it already exhaustively debated why this collection can't reasonably
just be called "std::pool" or some minor embellishment thereof?

It's just an unordered collection yielded from a simple growable,
discontiguous pool allocator.
Which a substantial portion (if not outright majority) of intended users
already understand.

It's a vastly lesser sin IMO to have a standard library collection sound
perhaps too close to an allocator implementation (-that it actually uses-)
than to stretch metaphors covering at best secondary distinguishing
characteristics into class names.

In addition to the very reasonable naming aspirations given by Nathan, I
would emphatically suggest:
- adopt well established names from systems programming patterns when
already available
- have meanings as friendly as possible to non-native English speakers (or
non liberal arts majors, random subject matter experts, etc.)

Also, if we truly require some qualifier to explicitly indicate
non-invalidation of iterators, I agree that "stabile" ought not be
overloaded and would suggest "steady" as an alternative.

--Jeff S.