negociate has 6 distinct synonyms spread across 3 of its 6 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.
sell or discount
“negociate securities”
Synonyms, antonyms and the broader and narrower relations for negociate come from Princeton University’s WordNet. Full sources and licences.
transfer by endorsement to another in return for value received
“negociate a bond”
confer with another in order to come to terms or reach an agreement
“The parties negociated all night”
discuss the terms of an arrangement
“They negotiated the sale of the house”