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Unified Medical Language System® (UMLS®)

Semantic Relationships at the Concept Level

Semantic relationships may or may not hold at the concept level.

For example, the relationship Clinical Drug causes Disease or Syndrome does not hold at the concept level for Aspirin and Cancer. Aspirin does not cause cancer. Not all relationships that apply at the concept level are indicated in the Semantic Network. Specifically:

Type 1 Relationship Type 2
Sign or Symptom evaluation of Organism Attribute


The above relationship does not hold between the concepts fever and body weight. Fever is not an evaluation of body weight.

Click on the image below to expand the graphical representation of a portion of the UMLS Semantic Network.

click to see a portion of the Semantic Network

Last Reviewed: July 29, 2016