WordNet records no synonym and no antonym for none. 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.
a canonical hour that is the ninth hour of the day counting from sunrise
a service in the Roman Catholic Church formerly read or chanted at 3 PM (the ninth hour counting from sunrise) but now somewhat earlier
2 of the 4 recorded senses carry no synonym, antonym or related term, so they are not shown above. Every sense, with its definition and examples, is on the full entry for none.
Synonyms, antonyms and the broader and narrower relations for none come from Princeton University’s WordNet. Full sources and licences.