sisterhood has 1 distinct synonym spread across 2 of its 3 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.
the kinship relation between a female offspring and the siblings
an association or society of women who are linked together by a common religion or trade or interest
a religious society of women who live together as sisters (especially an order of nuns)
Synonyms, antonyms and the broader and narrower relations for sisterhood come from Princeton University’s WordNet. Full sources and licences.