frontier

Từ điển Oxford Advanced Learner 8th

fron·tier [frontier frontiers] BrE [ˈfrʌntɪə(r)] NAmE [frʌnˈtɪr] noun
1. (BrE)countable a line that separates two countries, etc; the land near this line
•~ (between A and B) the frontier between the land of the Saxons and that of the Danes
•~ (with sth) a customs post on the frontier with Italy
•a frontier town/zone/post
2. the frontiersingular the edge of land where people live and have built towns, beyond which the country is wild and unknown, especially in the western US in the 19th century
•a remote frontier settlement
3. countable, usually plural ~ (of sth) the limit of sth, 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)
•to roll back the frontiers of government (= to limit the powers of the government)

Word Origin:
late Middle English: from Old French frontiere, based on Latin frons, front- ‘front’.

Synonyms:
border
boundary • frontier
These are all words for a line that marks the edge of sth and separates it from other areas or things.
border • the line that separates two countries or areas; the land near this line: ▪ a national park on the border between Kenya and Tanzania
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.
frontier • (BrE) the line that separates two countries or areas; the land near this line: ▪ The river formed the frontier between the land of the Saxons and that of the Danes.
which word?
The point where you cross from one country to another is usually called the border. In British English it can also be called the frontier, but this is often in a context of wildness, danger and uncertainty: ▪ The rebels control the frontier and the surrounding area. 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
across/along/on/over a/the border/boundary/frontier
at the boundary/frontier
the border/boundary/frontier with a place
the northern/southern/eastern/western border/boundary/frontier
a national/common/disputed border/boundary/frontier

Example Bank:
•America's wild frontier
•France's frontier with Germany
•Many people travelling across the frontier were illegal immigrants.
•Neither country would guarantee the integrity of their common frontier.
•Space is the final frontier for us to explore.
•The army crossed the frontier in the middle of the night.
•The rebels control the frontier and the surrounding area.
•The scientists' work will push back the frontiers of physics.
•There was an army checkpoint at the frontier.
•There were very few border controls on the south-western frontier.
•They were forced to retreat back over the frontier.
•an army grouping along the frontier
•people living on the German frontier
•the frontier between India and Pakistan
•I was searched by border guards on the frontier in Kuwait.
•Is space the final frontier?
•The river formed the frontier between the land of the Saxons and that of the Danes.
•This research programme aims to push back the frontiers of science.