taperwise
/ˈteɪpərwaɪz/Definitions
1. adverb
in a tapering direction or manner, as if narrowing or becoming smaller
“The artist painted the landscape taperwise, gradually decreasing the colors from the horizon.”
2. adverb
from or in the direction of the taper, or a tapering part
“The sound waves propagated taperwise through the medium, gradually losing their intensity.”