1."a word"中的word意为字、词,系可数名词
2.words如果不作word的复数,意为言语、话语,系集体名词.比如Your words is rather comment than description（你的言语并非描述而是评论）.
3.words作言语解时,用单数,但不能用“a words”,应为“a piece of words”.
4.口语中时见“one words to describe yourself”,系由“one word to describe yourself”混用,前者在语法上是不对的,但是含义准确无误,且避免了用sentence比较呆板.前者意为“一句话描述自己”,后者意为“一个词描述自己”.
5.“用一句话介绍你一下”
口语版 please describe yourself in one words
书面版 would you please describe yourself within one sentence?