No I'm not. The word is used interchangeably but the role has a very precise meaning. We call bulkier classes "tanky". Because they are not tanks but have higher defenses like a tank does.
If the game isn't designed around the trinity, the role "tank" has absolutely no point. In DnD we use meatshield, in Moba we use "bruiser" or "initiator" or "durable", usually to describe the top laners. Only in mmos we use the word "tank".
Semantics.
A "meatshield" in DnD is a tank. The meatshield absorbs damage while holding aggro. That is a tank. They didn't use the word "tank" perhaps, but the meaning is the same.
A bruiser is a multiclass unit that has different ITEM builds for the same ability set, so they cannot be used in this discussion. They are tanks when built tanky and dps when built for dps. They can be "both", but something that can tank is a tank, albeit inefficently if not enough tank items are bought.
LoL (and other MOBAs) also has dedicated tanks that are only efficient at tanking.
So basically MOBA tanks are different in that their items make them tanks, rather than their abilities, with the units with abilities specialized for tanking being better at it. A support can build tanky and be a hell of a tank, but a dedicated tank will always be better.
It's different than RPGs.