Can we call a heuristic (especially a meta-heuristic) a solver? I am not so sure.
Warning: this is somewhat of an opinionated rant. Many of you may not agree.
The name "solver" seems to imply that the underlying algorithm knows when an optimization problem is solved. By that I mean: it can stop at some stage and report "solved". Meta-heuristics typically don't have a clue about optimality, and just keep on churning until hitting some form of time or iteration limit. (One could devise some stopping criteria basic on stochastic reasoning, but that is not often used in meta-heuristics).
So my proposal is:
Heuristics (including meta-heuristics) should not be called solvers. They don't know when a problem is solved.