adulterating has 1 distinct synonym spread across 1 of its 1 sense. 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 purifying.
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.
making impure or corrupt by adding extraneous materials
“the adulterating effect of extraneous materials”
Synonyms, antonyms and the broader and narrower relations for adulterating come from Princeton University’s WordNet. Full sources and licences.