1. not having official papers or records to prove something
2. lacking proper legal documents, especially referring to immigrants without valid visas or permits
Usage: often used in immigration contexts

Examples

• The researcher found several undocumented species in the rainforest.
• Many undocumented workers contribute to the local economy.
• The software had undocumented features that users discovered by accident.
• Undocumented immigrants often live in fear of deportation.
• The historian uncovered undocumented events from the war.
• The company hired undocumented employees without proper verification.