UMLS Concept Unique Identifier

**Semantic type:** Conceptual Entity

**Definition:** In the Unified Medical Language System (UMLS) of the National Library of Medicine (NLM) the concept unique identifier (CUI) is an 8-character identifier beginning with the letter "C" and followed by 7 digits. Each concept is assigned such a CUI. The CUI has no intrinsic meaning but remains constant through time and across versions.

**Synonyms:** - CUI - NLM CUI - UMLS CUI