- 1[countable] a line that separates two countries, etc.; the land near this line frontier (between A and B) the frontier between Guatemala and Mexico frontier (with something) a customs station on the frontier with Brazil a frontier town/zone Thesaurusborder
- boundary
- frontier
- barrier
- border the line that separates two countries or areas; the land near this line:a national park on the border between Montana and Wyoming
- boundary a line that marks the edges of an area of land and separates it from other areas:The fence marked the boundary between my property and hers.
- The point where you cross from one country to another is usually called the border. The line on a map that shows the border of a country can be called the boundary, but “boundary” is not used when you cross from one country to another:After the war, the national boundaries were redrawn. Thousands of immigrants cross the boundary every day.Boundary can also be a physical line between two places, for example between property belonging to two different people, marked by a fence or wall:the boundary fence/wall between the properties
- frontier the border between two countries or areas; a line that marks the beginning of an unexplored or dangerous area:the frontier between Guatemala and Mexico The Ingalls family crossed the frontier in a covered wagon.
- barrier something that exists between two places and prevents easy movement between them:The mountains form a natural barrier between the ocean and the desert.
- across/along/on/over a/the border/boundary/frontier/barrier
- at the boundary/frontier/barrier
- the border/boundary/frontier with a place
- the northern/southern/eastern/western border/boundary/frontier
- a national/common/disputed border/boundary/frontier
- 2the frontier [singular] the edge of land where people live and have built towns, beyond which the country is wild and unknown, especially in the western U.S. in the 19th century a remote frontier settlement
- 3[countable, usually plural] frontier (of something) the limit of something, especially the limit of what is known about a particular subject or activity to push back the frontiers of science (= to increase knowledge of science)
Check pronunciation: frontier