Sector SECTOR General term used to describe a group of establishments engaged in similar kinds of economic activity. A sector can be a subgroup of an economic activity - as in "coal mining sector" - or a group of economic activities - as in "service sector" - or a cross-section of a group of economic activities - as in "informal sector". "Sector" is also a specific term used in the 1993 United Nations System of National Accounts to denote one of the five mutually exclusive institutional sectors that group together institutional units on the basis of their principal functions, behaviour and objectives, namely: nonfinancial corporations, financial corporations, general government, non-profit institutions serving households (NPISHs) and households. String Codelist