WordNet records no synonym and no antonym for reverse osmosis. 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.
(chemistry) a method of producing pure water; a solvent passes through a semipermeable membrane in a direction opposite to that for natural osmosis when it is subjected to a hydrostatic pressure greater than the osmotic pressure
Synonyms, antonyms and the broader and narrower relations for reverse osmosis come from Princeton University’s WordNet. Full sources and licences.