A patent troll is a derogatory term used to describe a company that uses patent infringement claims to win court judgments for profit or to stifle competition. The term may be used to describe a number of business activities that utilize patents and the court system to earn money.

（From：https://www.investopedia.com/terms/p/patent-troll.asp）

Investopedia给出如上定义。

笔者并未查到官方对应中文，但在网上查到如下释义：从破产的企业便宜地买下专利，再基于该专利告被疑侵害企业专利侵害，通常不管自己是否有实施依该专利权的发明，而请求高额的授权金，patent troll系指此种人。

PS: Troll在《新牛津英汉双解大词典》中给出的释义为：a mythical, cave-dwelling being depicted in folklore as either a giant or a dwarf, typically having a very ugly appearance（尤指民间传说中相貌奇丑的）穴居巨人（或侏儒）。