WordNet records no synonym and no antonym for reinsure. It is the only member of each of its synsets, 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.
insure again by transferring to another insurance company all or a part of a liability assumed
insure again by assuming all or a part of the liability of an insurance company already covering a risk
Synonyms, antonyms and the broader and narrower relations for reinsure come from Princeton University’s WordNet. Full sources and licences.