When a tax takes a larger percentage on income from a-low income earners than from high income earners it is called?

What we have in the United States is a Progressive tax system where the higher your income the higher the percentage of income tax you pay. I guess the other way around would be a regressive tax system. The United States is approaching a very dangerous point. It is getting closer and closer to a point where over half of the people in the Country pay no income taxes at all. When you get to this point, the majority of voters would not care what the taxes were at all so they could vote to take more and more from those who build your economy and who provide jobs. This would take away all incentive to produce and provide an economy.