This short paper highlights some new work being performed at the National Centre for Classification in Health (NCCH), relating newly created term sets developed for specific purposes to existing reference terminologies and classifications such as SNOMED CT and ICD-10-AM. It describes some of the inherent difficulties experienced by the NCCH team in interpreting terms in the term set and therefore in locating equivalent concepts in reference terminologies and classifications, in the absence of a context with which to associate each term. Also examined is the effect that a person's background and past experience has on their understanding and interpretation of clinical terms and how this results in inconsistent "world views".