WordNet records no synonym and no antonym for contextual definition. It is the only member of its synset, which is common for technical, taxonomic and single-sense vocabulary — there is no other English word that means the same thing. The broader and narrower terms below are the useful relations in that case.
Counts are distinct word forms across every sense. A synonym that appears under three senses is counted once here and shown three times below, under each sense it belongs to.
a definition in which the term is used by embedding it in a larger expression containing its explanation
“a contextual definition of `legal duty' might be `X has a legal duty to do Y means that X is required to do Y by a contract relationship that would be upheld in a court of law'”
Synonyms, antonyms and the broader and narrower relations for contextual definition come from Princeton University’s WordNet. Full sources and licences.