WordNet records no synonym and no antonym for mecca. It is the only member of each of its synsets, 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.
joint capital (with Riyadh) of Saudi Arabia; located in western Saudi Arabia; as the birthplace of Muhammad it is the holiest city of Islam
a place that attracts many visitors
“New York is a mecca for young artists”
Synonyms, antonyms and the broader and narrower relations for mecca come from Princeton University’s WordNet. Full sources and licences.