FRONTIER

noun Etymology: Middle English fronter, from Anglo-French frountere, fronter, from front Date: 15th century 1. a border between two countries, a stronghold on a ~, 2. a region that forms the margin of settled or developed territory, the farthermost limits of knowledge or achievement in a particular subject, a line of division between different or opposed things , a new field for exploitative or developmental activity, ~ adjective