It's the opposite, in that instead of the jury overruling the judge on law (normally the province of the judge), the judge overrules the jury on the ultimate factual question of liability (normally the province of the jury). The required showing is accordingly exacting (though hardly impossible to meet in practice): no rational jury could have reached the same conclusion.

Do you know where to find the definition of rational that applies in these cases?

In a sense, in that you could view any post-verdict judgement contrary to the verdict as a ruling that the jury attempted nullification of the law where it lacks the power to do so (nullification is only a power juries can exercise to return criminal not-guilty verdicts, other than that, courts may set aside the jury verdict of no reasonable jury could find the facts necessary to the verdict returned on the evidence presented.)