taper       
 verb [ I or T ] uk/ˈteɪ.pər/ us/ˈteɪ.pɚ/
 (使)一端逐渐变窄
to become gradually narrower at one end, or to make something do this
  Then you'll come to a place where the pavement tapers off and the dirt road begins. 然后你就会走到一个地方,人行道逐渐变窄,然后变成泥地。 
 Phrasal verb   
taper off 逐渐变小;逐步减弱
to become gradually smaller or weaker, or happen less often
  Her voice tapered off as she realized everyone was listening. 当她意识到大家都在听时,她的声音就越来越小了。 
 Sales have gradually tapered off. 销售额逐渐下滑。 
 taper      
noun [ C ] uk/ˈteɪ.pər/ us/ˈteɪ.pɚ/
 细枝小蜡烛; 点火木片;灯芯;烛芯
a very thin candle or a very thin strip of wood, used especially in the past for lighting candles, fires, etc.