Synonyms for Tapering (same or very similar meaning)
WordNet sense 1 (becoming gradually narrower):
tapered, narrowingWordNet sense 2 (gradually decreasing until little remains):
dwindling, tapering offWordNet sense 3 (becoming less or smaller):
decreasingWordNet sense 4 (not wide):
narrowWordNet sense 5 (having a point):
pointedFrom the ODE community, based on WordNetadd/edit