Weaponized patent is a slang term that refers to patents that are filed with the intent of using them to sue competitors who are developing similar technologies.
Patent wars have become increasingly common among high-tech companies since the 1990s. In recent years, however, the game has shifted from a drive to protect unique technologies and inventions to a business strategy in which some struggling companies appear to be using patents as a last-ditch attempt to generate revenue. This has forced many large tech companies to buy and stockpile patents as a means of defense against these lawsuits.
Techopedia explains Weaponized Patent
Developers have been especially critical of the use of patents as a litigation tool, claiming that they were designed to defend against - rather than launch - patent infringement lawsuits. Most significantly, the merit of many weaponized patents has been called into question because they tend to contain vague wording, making it easier to apply them to other similar (and often relatively generic) technologies.
The term weaponized patent was popularized by a March 2012 article by Andy Baio for Wired.com, where he explained how Yahoo's patents on software he created were used in a lawsuit against Facebook. Baio calls Yahoo's lawsuit against Facebook "nothing short of extortion," claiming that one of the patents he co-invented - and that was later used in Yahoo's suit against Facebook - was so abstract that it could have been used against a number of other companies. As it turned out, Facebook defended itself against Yahoo's suit for 10 patents by suing Yahoo with 10 patents from its own patent collection.