> Tail calls can be implemented without adding a new stack frame to the call stack. Most of the frame of the current procedure is no longer needed, and can be replaced by the frame of the tail call, modified as appropriate (similar to overlay for processes, but for function calls). The program can then jump to the called subroutine. Producing such code instead of a standard call sequence is called tail-call elimination or tail-call optimization. (https://en.wikipedia.org/wiki/Tail_call)
I suppose maybe TCE (as distinct from TCO) should be expanded to include any mechanism that doesn't expand the stack / heap / whatever for things that rhyme with recursion (in which case the existing sloppiness may as well stand, but we need a new TLA).
Not really, a trampoline could emulate them effectively where the stack won't keep growing at the cost of a function call for every opcode dispatch. Tail calls just optimize out this dispatch loop (or tail call back to the trampoline, however you want to set it up).