WordNet records no synonym and no antonym for ram disk. 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.
(computer science) a virtual drive that is created by setting aside part of the random-access memory to use as if it were a group of sectors
“access to a RAM disk is very fast but the data it contains is lost when the system is turned off”
Synonyms, antonyms and the broader and narrower relations for ram disk come from Princeton University’s WordNet. Full sources and licences.