decimalise has 1 distinct synonym spread across 2 of its 2 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.
change from fractions to decimals
“Stock prices will be decimalized in the year 2000”
change to the decimal system
“The country decimalized the currency in 1975”
Synonyms, antonyms and the broader and narrower relations for decimalise come from Princeton University’s WordNet. Full sources and licences.