territorial authority that exercises the functions, duties and powers of both a regional council and a city or district council. There are four unitary authorities in New Zealand - Nelson City Council, and Tasman, Marlborough and Gisborne District Councils. (NZ)

a term used in a two-tier local government system to describe a unit of local government that operates as a single tier

Unitary authorities, like Plymouth City Council, were created as part of local government reorganisation between 1996 and 1998. They provide a full range of local authority services.