[camiller]

They are not well defined terms and are meant more to evoke an emotional response. Progressive does mean that you pay at an increasing rate the higher your income is. A flat percentage tax (example everyone pays 18% no loopholes) should be neither progressive or regressive but most US liberals would still call it regressive because it would be if you consider the current rates as a baseline. A truly regressive plan would actually decrease rates as you went higher in income. Neither Federal or any state that has income taxes has a truly regressive tax schedule.

Edit: I suppose if you figure in sales taxes into overall tax burden you could call some states regressive. But that is not a feature of their income tax rates.