Longman Dictionary of Contemporary English - constituency

~ n 1 an area of the country that elects a representative to a parliament  (John Major, speaking from his Huntingdon constituency) 2 (also + plural v BrE) the people who live and vote in a particular area  (- compare ward1 (2)) 3 any group that supports or is likely to support a politician or a political party  (The Unions were no longer the constituency of the Labour Party alone.)