Definitions of patent troll
a person or company that is granted a patent (=the rights to use or license an invention) and then demands payment to use them while making few if any products of their own. Patent trolls are set up with the sole aim of litigating and making money through claims related to their patents.
"Patent trolls use bad patents to bully companies of all sizes, in every economic sector, from coast to coast," said Michael Beckerman, President of The Internet Association.