What's the definition of a grinder in chess?

They say, Carlsen grinded, Grischuk grinded … what does it mean? That they kept playing precise moves deep in the endgame and their opponents didn't? Personally, I think it is a very elegant way of winning a chess game. And the word grind does not resemble any of that.

I mean, the cuban Capablanca was a real gentleman...to say that he grinded his opponents and regularly beat them in simple (for him) positions, sounds so bad ah ah

I think it is meant as a compliment. Something along the lines of it was a difficult game/position, but they stuck with it and won.

First of all, 'to grind' is an irregular verb: grind - ground - ground.

As far as I understand it, that a chess player ground an opponent means that the former didn't crush fast but rather held a slow but deadly grip, playing a possibly simplified but solid game, making use of slight weaknesses and increasing the advantage gradually. Think of the solid Maroczy Bind, as opposed to the risky (but impressive) Triple Muzio Gambit.

Compare that to the definition of a grind in online poker - it means playing at a lot of tables at once (and hence more hands an hour) but with an inevitably smaller average winrate (in $/hand) than if playing at few tables and focusing on every decision to earn more $ per hand at the same stakes, or playing at higher and riskier stakes.

In live poker, the term 'grind' refers to a different kind of trading quality for quantity, namely, playing for many hours a day, which also leads to the fall of the quality of decisions and the winrate per hand because of exhaustion, but may increase the weekly winrate. (This aspect certainly applies to online games too.)

Even in chess, observe that people who play hundreds of correspondence games at once (it seems to be a Filipino national trait) have lower ratings than they'd achieve if spending more time to think moves through. I call them grinders too, though they can't be admired as much as Capablanca or Carlsen.

but it's more swindling