process has 19 distinct synonyms spread across 11 of its 13 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.
deal with in a routine way
“I'll handle that one”
perform mathematical and logical operations on (data) according to programmed instructions in order to obtain the required information
“The results of the elections were still being processed when he gave his acceptance speech”
a particular course of action intended to achieve a result
“the procedure of obtaining a driver's license”
(psychology) the performance of some composite cognitive activity; an operation that affects mental contents
“the process of thinking”
a mental process that you are not directly aware of
“the process of denial”
a sustained phenomenon or one marked by gradual changes through a series of states
“events now in process”
Synonyms, antonyms and the broader and narrower relations for process come from Princeton University’s WordNet. Full sources and licences.