uselessness 

英汉解释

n. 无用，无效

同义词

n. inutility，unusefulness

反义词

n.   usefulness，utility

参考例句

1. "To make you see the uselessness of having one".
让你看到拥有的是无用的东西。
2. Well, uselessness can be turned into usefulness.
可以化无用为有用。
3. Many people have the impression that old age represents uselessness, senility, and the approach of death.
很多人觉得年老代表无用、衰老和步向死亡。

英英解释

n.
  1. the quality of having no practical use

网络释义

uselessness
无用;
feeling of uselessness
无用感 社会福利; 无用感;
a feeling of uselessness
一种无能为力的感觉;