conservation has 1 distinct synonym spread across 1 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.
an occurrence of improvement by virtue of preventing loss or injury or other change
the preservation and careful management of the environment and of natural resources
(physics) the maintenance of a certain quantities unchanged during chemical reactions or physical transformations
Synonyms, antonyms and the broader and narrower relations for conservation come from Princeton University’s WordNet. Full sources and licences.