(patent law, derogatory) A person or company that enforces copyrights that it owns for purposes of generating income through strategic litigation, in a manner considered unduly aggressive or opportunistic.

(copyright law) The unauthorized use of copyrighted material in a manner that violates one of the copyright owner's exclusive rights, such as the right to reproduce or perform the copyrighted work, or to make derivative works that build upon it.

plural of copyright infringement

(informal) The practice of mailing a sealed, dated copy of one's work to oneself as a proof of copyright ownership, rather than registering the work with a copyright office.