Word History Etymology Noun Middle English bordure, from Anglo-French, from border to border, from Old French bort border, of Germanic origin; probably akin to Old English bord board

BORDER definition: the part or edge of a surface or area that forms its outer boundary. See examples of border used in a sentence.

U.S. Customs and Border Protection: Protecting the American people, safeguarding our borders and enhancing the nation’s economic prosperity.

Phrasal verb border on something (Definition of border from the Cambridge Advanced Learner's Dictionary & Thesaurus © Cambridge University Press)

Most external political borders are partially or fully controlled, and may be crossed legally only at designated border checkpoints; adjacent border zones may also be controlled. For the purposes of …

the part of an area that forms its outer boundary; the line that separates one area, state, or country from another; periphery: They are building a fence along the border.

Sep 5, 2025 · A border is a physical or political line that separates geographic areas. This wall sits on the border between the United States and Mexico near the Mexican city of Tijuana.