WordNet records no synonym and no antonym for calais. It is the only member of its synset, which is common for technical, taxonomic and single-sense vocabulary — there is no other English word that means the same thing. The broader and narrower terms below are the useful relations in that case.
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 town in northern France on the Strait of Dover that serves as a ferry port to England; in 1347 it was captured by the English king Edward III after a long siege and remained in English hands until it was recaptured by the French king Henry II in 1558
Synonyms, antonyms and the broader and narrower relations for calais come from Princeton University’s WordNet. Full sources and licences.