1. (of taxes) adjusted so that the rate decreases as the amount of income increases
   "Critics argued that the regressive sales tax disproportionately affected low-income households"
    
2. Opposing progress; returning to a former less advanced state
   "The regressive policies threatened to undo years of social advancement"

See also: atavistic, backward, retrograde, retrogressive, returning, reverting, throwback, unmodernised [Brit], unmodernized

Antonym: progressive