The Collaborative International Dictionary
degressive
degressive \degressive\ adj.
going down by steps.
gradually decreasing in rate on sums below a certain amount. [WordNet 1.5] ||
Wiktionary
degressive
a. 1 Tending to decrease 2 Decreasing in steps
WordNet
degressive
adj. going down by steps
gradually decreasing in rate on sums below a certain amount