conserve has 8 distinct synonyms spread across 3 of its 5 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. Its one recorded opposite is waste.
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.
keep constant through physical or chemical reactions or evolutionary change
“Energy is conserved in this process”
keep in safety and protect from harm, decay, loss, or destruction
“We preserve these archeological findings”
preserve with sugar
“Mom always conserved the strawberries we grew in the backyard”
fruit preserved by cooking with sugar
Synonyms, antonyms and the broader and narrower relations for conserve come from Princeton University’s WordNet. Full sources and licences.