Someone's going to have to explain the word "populist" to us

The idea that someone standing for election should promise things that the populace might like to vote for seems to us to be rather the point of the system. And, as Mencken said, democracy means they then get it good and hard.

Milei, in Argentina, diagnosed that the entire Argentinian state, its economics, its management - in both senses, what is done and who is doing it - is rotten and needs to be swept away. He got elected. Of course, for all those others who are part of the management of other states this poses something of a risk. What if it works and then their own restive managees decide to do the same? We’d thus expect the establishments of everywhere else to not just denigrate but actively block anything Milei tries to do. As, of course, the domestic managerial class will also be trying to do the same.

We do indeed think that it’s possible for a place to be so badly run that only truly radical action will restore matters. We are not conservatives, we are classical liberals after all - neoliberals even.

But perhaps someone could explain this to us:

“Fiery right-wing populist Javier Milei wins Argentina’s presidency and promises ‘drastic’ changes”

Why is he being described as a populist? Other than in that manner of proposing things that the electorate might find popular that is?

For we’ve also had this in this same election:

Argentina will exempt millions of workers from paying income taxes, a dramatic attempt by Economy Minister Sergio Massa to improve his standings in next month’s presidential election at the risk of deepening the country’s fiscal hole.

Workers earning less than 1.7 million pesos ($4,857) per month won’t have to pay income taxes as of October, up from the previous threshold of about 700,000 pesos, Massa said Monday in Buenos Aires. The measure means only 90,000 top executives and high-ranking managers across the country will have to pay the tax, he said. That’s less than 1% of total registered workers.

The incumbent finance minister essentially abolishes income tax (not a bad idea!) and still loses. But it’s his opponent, the other guy, who is described as the populist?

Other than “populist” merely meaning someone the managerial class doesn’t like what does it actually mean?