1 a part of the business activity of a country 国家经济的一部份；部门: The manufacturing sector has declined in recent years. 近年来制造业日渐衰落。the public/private sector 公营╱私营部门

2 a part of an area or of a large group of people （某地区或一大群人中的）一部份: the Christian sector of the city 该市的基督徒群体

3 (mathematics数学) a part of a circle that is between two straight lines drawn from the centre to the edge 扇形 ☞picture at circle 见circle插图