WordNet records no synonym and no antonym for caliphate. 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.
the era of Islam's ascendancy from the death of Mohammed until the 13th century; some Moslems still maintain that the Moslem world must always have a calif as head of the community
“their goal was to reestablish the Caliphate”
the territorial jurisdiction of a caliph
Synonyms, antonyms and the broader and narrower relations for caliphate come from Princeton University’s WordNet. Full sources and licences.