UEN stands for Unique Entity Number, which is a standard identification number used by entities to interact with government agencies in Singapore. It uniquely identifies an entity, similar to how the NRIC is used for Singapore Citizens and Permanent Residents.

A UEN is issued by government agencies, known as UEN-issuance agencies, when an entity is officially registered. Some examples of these agencies include the Accounting and Corporate Regulatory Authority (ACRA), Registry of Societies (ROS), and Ministry of Manpower (MOM).