plot has 7 distinct synonyms spread across 4 of its 8 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.
a secret scheme to do something (especially something underhand or illegal)
“they concocted a plot to discredit the governor”
a small area of ground covered by specific vegetation
“a bean plot”
a chart or graph showing the movements or progress of an object
plan secretly, usually something illegal
“They plotted the overthrow of the government”
devise the sequence of events in (a literary work or a play, movie, or ballet)
“the writer is plotting a new novel”
Synonyms, antonyms and the broader and narrower relations for plot come from Princeton University’s WordNet. Full sources and licences.