TAPER

(BECOME NARROW) [verb] - to (cause to) become narrower or reduced in some wayThe river soon tapers into a stream as you follow it up the mountain. [I]The stick was tapered to a point. [T]You'll have to taper it to make it fit. [T]Turn left where the road tapers (off) into a track. [I]Her voice tapered off as she realised everyone was listening. [I]We had a lot of interest in the book, but it has tapered off recently. [I]She had long tapering fingers