WordNet records no synonym and no antonym for mortgage-backed security. 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 security created when a group of mortgages are gathered together and bonds are sold to other institutions or the public; investors receive a portion of the interest payments on the mortgages as well as the principal payments; usually guaranteed by the government
Synonyms, antonyms and the broader and narrower relations for mortgage-backed security come from Princeton University’s WordNet. Full sources and licences.