Definition - What does Orphan Work mean?
An orphan work is legally protected material whose owner cannot be readily identified or located. The term is generally employed in cases in which someone who holds a copyright passes away without assigning it to someone else, or when they don't know that they actually own it.
Justipedia explains Orphan Work
In the United States, libraries will not shelf any material classified as an orphan work for fear of legal reprisal. The concern is that the copyright holder could come forward and recover up to $150,000 in damages.
The U.S. Copyright Office has also acknowledged that ambiguity regarding the ownership of legally protected material is a significant concern in many countries. Specifically, the organization notes that it creates potential liability and is a significant source of aggravation for those seeking permission to use the material. Furthermore, the U.S. Copyright Office says it creates unnecessary logjams in the "digital marketplace." These concerns prompted the U.S. Copyright Office to issue a report titled: "Orphan Works and Mass Digitization: A Report of the Register of Copyrights."