sector has 1 distinct synonym spread across 1 of its 6 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.
a plane figure bounded by two radii and the included arc of a circle
a social group that forms part of the society or the economy
“the public sector”
Synonyms, antonyms and the broader and narrower relations for sector come from Princeton University’s WordNet. Full sources and licences.
a particular aspect of life or activity
“he was helpless in an important sector of his life”
the minimum track length that can be assigned to store information; unless otherwise specified a sector of data consists of 512 bytes
measuring instrument consisting of two graduated arms hinged at one end