border
Word family
- borderlineadjectiveC1
- borderlessadjectiveC1
Synonym discussion
Sense: noun/1
For the line between countries or areas, 'border' is the normal everyday word, especially in news about travel, trade, or immigration. 'Boundary' is slightly more formal and works for many kinds of dividing lines, such as between properties, fields, or areas of study, so it is wider in use. 'Frontier' often suggests the outer edge of a country or a more distant, less settled region, not only a precise legal line. 'Edge' is much broader and usually means the outer limit of an object or place, not an official division. So you cross a border at a checkpoint, mark a property boundary with a fence, describe a wild frontier far from cities, and stand at the edge of a cliff.
Etymology
Border came into English from Old French bordure, a word for an edge or trimming around something. That French form was built from bord, meaning an edge or rim, and it is related to Germanic words behind English 'board'. From the idea of an outer edge, English later developed the sense of the line separating one place from another.