the less harmful or unpleasant of two bad choices or possibilities兩害之較輕者；兩種不愉快中較小者
英語四級真題
The high cost of steam and the lesser need for speed kept the majority of the world's ocean freight moving by sail until the early years of the 20th century.
出自-2014年6月閱讀原文
英語六級真題
The Cascadia Earthquake Zone is big enough to compete with San Andreas it's been called the most dangerous fault in Americ, but it's much lesser known than its California cousin.
2019年12月六級真題（第一套）閱讀 Section C
柯林斯高階英漢雙解學習詞典釋義
ADJ-COMPAR
較少的；較輕的；較小的
You use lesser in order to indicate that something is smaller in extent, degree, or amount than another thing that has been mentioned.