concord has 14 distinct synonyms spread across 7 of its 10 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.
capital of the state of New Hampshire; located in south central New Hampshire on the Merrimack river
town in eastern Massachusetts near Boston where the first battle of the American Revolution was fought
the first battle of the American Revolution (April 19, 1775)
arrange by concord or agreement
“Concord the conditions for the marriage of the Prince of Wales with a commoner”
arrange the words of a text so as to create a concordance
“The team concorded several thousand nouns, verbs, and adjectives”
Synonyms, antonyms and the broader and narrower relations for concord come from Princeton University’s WordNet. Full sources and licences.