equivalence relation

n.The association between terms that, for indexing purposes, are treated as the same concept.

Notes

In thesaurus construction, preferred and nonpreferred (lead-in) terms are associated using 'use' and 'use for'. One term is established as the preferred term, and equivalent terms point to that term. The terms may not be exactly synonymous, but the preferred term is used to bring closely related concepts together for improved access.