A concept without a sufficient definition in the necessary normal form distributed in the relationship.
The meaning of a SNOMED CT concept is expressed in a human-readable form by its fully specified name. Each concept also has a formal concept definition that provides a computer-processable representation of the meaning of the concept.
A primitive concept has a concept definition that is not sufficient to computably distinguish it from other concepts.
The concept 5596004 | atypical appendicitis (disorder)| is primitive because the following definition is not sufficient to distinguish atypical appendicitis from any other type of appendicitis:
Changes introduced in the July 2018 release of the International Edition allow assertions to be represented as axioms in the OWL axiom reference set file. This will allow concepts to be defined by multiple sufficient definitions, some of which may contain assertions that are not necessarily true.