You can use tail to refer to the end or back of something, especially something long and thin. (尤指细长物体的) 尾部
adjective [原级] 有……尾的；去掉尾的
'But why...?' Her voice tailed away. “但是为什么…？”她的声音细了下去。
verb [vt. 及物动词] 尾随（tail 的过去式及过去分词）
Last year, economic growth tailed off to below four percent. 去年，经济增长率逐渐降到了4%以下。
