mixture has 15 distinct synonyms spread across 4 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. 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.
(chemistry) a substance consisting of two or more substances mixed together (not in fixed proportions and not with chemical bonding)
any foodstuff made by combining different ingredients
“he volunteered to taste her latest concoction”
a collection containing a variety of sorts of things
“a great assortment of cars was on display”
an event that combines things in a mixture
“a gradual mixture of cultures”
Synonyms, antonyms and the broader and narrower relations for mixture come from Princeton University’s WordNet. Full sources and licences.