idealization has 2 distinct synonyms spread across 3 of its 3 senses. Each sense below keeps its own list, because a synonym belongs to a meaning and not to a word: swapping one sense's substitute into another sense's sentence is how a thesaurus makes writing worse. WordNet records no antonym for it — antonymy is a relation between word forms rather than concepts, so it is deliberately sparse.
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 portrayal of something as ideal
“the idealization of rural life was very misleading”
(psychiatry) a defense mechanism that splits something you are ambivalent about into two representations--one good and one bad
Synonyms, antonyms and the broader and narrower relations for idealization come from Princeton University’s WordNet. Full sources and licences.