I'm not OP, but I'll take a shot.

Trickle down economics is a pejorative which amounts to "cut taxes on the rich, and let the profits rain down on the rest of us".

It's a term invented to critique supply side economics whose idea is that reducing barriers to production will result in increased government revenue.

In my opinion, the study of supply side economics has been warped by its critics who oppose the rich paying lower and lower rates of income tax. They do not see that one of the original selling points was for the US government to receive more in tax revenue by lowering business costs to increase productivity.

I'll concede that the increased revenue is not going to the workers, but it wouldn't have gone to the workers in the absence of these economic policies either.

So I do believe that people who use the term "trickle down" (which is a political term used by politicians and pundits and not one that any economist would use) have taken a narrow part of supply side economics and mischaracterized it.