charles has 13 distinct synonyms spread across 9 of its 9 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.
King of France from 1560 to 1574 whose reign was dominated by his mother Catherine de Medicis (1550-1574)
King of France who began his reign with most of northern France under English control; after the intervention of Jeanne d'Arc the French were able to defeat the English and end the Hundred Years' War (1403-1461)
as Charles II he was Holy Roman Emperor and as Charles I he was king of France (823-877)
King of England and Scotland and Ireland during the Restoration (1630-1685)
son of James I who was King of England and Scotland and Ireland; was deposed and executed by Oliver Cromwell (1600-1649)
the eldest son of Elizabeth II and heir to the English throne (born in 1948)
French physicist and author of Charles's law which anticipated Gay-Lussac's law (1746-1823)
king of the Franks and Holy Roman Emperor; conqueror of the Lombards and Saxons (742-814)
a river in eastern Massachusetts that empties into Boston Harbor and that separates Cambridge from Boston
Synonyms, antonyms and the broader and narrower relations for charles come from Princeton University’s WordNet. Full sources and licences.