postscript
noun [ C ] uk/ˈpəʊst.skrɪpt/ us/ˈpoʊst.skrɪpt/
(abbreviation PS)（信末签名后的）附笔，又及
a short remark or message added to the bottom of a letter after you have signed your name, usually introduced by the abbreviation PS
There was the usual romantic postscript at the end of his letter - PS I love you. 他的信末又是一贯浪漫的附笔——附： 我爱你。
（正文后的）附言，补充说明
any written or spoken addition to something already finished
As a postscript to that story I told you last week, it turned out that the woman was his sister-in-law. 对上周我给你讲的那件事补充一句，那个女人原来是他妻子的妹妹。