1. A minor child whose parents have died, have relinquished their parental rights, or whose parental rights have been terminated by a court of jurisdiction.
2. Orphan (international adoption definition) For immigration purposes, a child under the age of sixteen years: whose parents have died or disappeared or who has been abandoned or otherwise separated from both parents or whose sole surviving parent is impoverished by local standards and incapable of providing that child with proper care and who has, in writing, irrevocably released the child for emigration and adoption. To enter the United States, an orphan must have been adopted abroad by a U.S. citizen or be admitted to the to the United States for the purpose of adoption by a U.S. citizen
Thanks to The National Adoption Information Clearinghouse