The original wording of this principle (given below) and content of this page is scheduled to be reviewed. Improved wording will be posted as it becomes available.


textual definitions (SOP) for a substantial and representative fraction, plus equivalent formal definitions (for at least a substantial number of terms). For terms lacking textual definitions, there should be evidence of implementation of a strategy to provide definitions for all remaining undefined terms.

Text definitions should be unique (i.e. no two terms should share a definition)

Date Accepted

  • original principle, modified

Clarifications required

  • What percentage of terms defined is acceptable?
  • Need clarification on
    • text definitions
    • text definitions written in formal style / genus differentia
    • computable definitions (i.e. equivalence axioms / cross-products)


Original Formulation

 The ontologies include textual definitions for all terms.

Many biological and medical terms may be ambiguous, so terms should be
defined so that their precise meaning within the context of a particular
ontology is clear to a human reader.