junk mail意思是：垃圾邮件。
junk mail：名词，垃圾邮件；（未经索要寄来的）邮寄广告宣传品，垃圾广告邮件。
双语例句
1、These days, we are bombarded with endless junk mail, fliers, and general bumf.
如今我们不得不面对铺天盖地的垃圾邮件、广告传单和无用的公文。
2、Malware reunion describes the situation
when a computer virus or other malware sendsjunk mail to recipients between you and someone on your contact list with whom you have not communicated in a long time.
Malware reunion说的是这样一个情景：你电脑中的某个病毒或恶意程序向你邮箱的联系人发送垃圾邮件，而这个垃圾邮件使得你跟好久没有联系的某个人又开始通信联系。我们可以称之为“因病毒重聚”。
3、An Algorithm of Chinese Keys Matching Used in Filtering Junk Mail.
一种用于垃圾邮件过滤的中文关键词匹配算法
4、A Way to Filter Junk Mail Intelligently Based on Machine Learning.
一种基于机器学习的垃圾邮件智能过滤方法
5、Research on Junk Mail and Its Management Problem.
垃圾邮件及其规制问题研究
"Junk mail" 是指垃圾邮件、广告邮件、垃圾广告信等，通常是指无效的邮件且没有被请求。
作为一个固定的短语，"junk mail" 有以下的用法：
1、指电子邮件中的垃圾邮件。如：I receive a lot of junk mail in my email account.
2、指买家收到的商家未经请求的广告邮件。如：I constantly receive junk mail from that company, despite my numerous attempts to unsubscribe.
3、指用户在信箱中收到的无用信件或广告信。如：I sort through my junk mail each day to make sure I don't miss any important mail.