In metadata, a synonym ring or synset, is a group of data elements that are considered semantically equivalent for the purposes of information retrieval. These data elements are frequently found in different metadata registries. Although a group of terms can be considered equivalent, metadata registries store the synonyms at a central location called the preferred data element.
According to WordNet, a synset or synonym set is defined as a set of one or more synonyms that are interchangeable in some context without changing the truth value of the proposition in which they are embedded.
The following are considered semantically equivalent and form a synonym ring:
foaf:person gjxdm:Person niem:Person sumo:Human cyc:Person umbel:Person
Note that each data element has two components:
A synonym ring can be expressed by a series of statements in the Web Ontology Language (OWL) using the classEquivalence or the propertyEquivalence or instance equivalence statement – the [[sameAs]] property.