Border
late Middle English: from Old French bordeure ; ultimately of Germanic origin and related to board.
wiktionary
Inherited from Middle English bordure, from Old French bordeure, of Germanic origin, from Frankish *bord, equivalent to modern French bord(“a border”) + -er.
Akin to Middle High German borte(“border, trim”), German Borte(“ribbon, trimming”). Doublet of bordure. More at board.
etymonline
border (n.)
mid-14c., bordure, in heraldry, "broad, colored band surrounding the shield," from Old French bordeure "seam, edge of a shield, border," from Frankish *bord or a similar Germanic source (compare Old English bord "side;" see board (n.2)). The form of the ending changed after c. 1500. From late 14c. as "edge, side, brink, margin," also "ornamental border along the edge of a dish, garment, etc." Italian and Spanish bordo also are from Germanic.
Sense of "boundary of a city or country" is from late 14c. From c. 1400 as "border region, district lying along the boundary of a country" (replacing earlier march). In U.S. history, "the line between the wild and settled regions of the country" (1827).
border (v.)
c. 1400, "to put a border on;" 1530s as "to lie on the border of," from border (n.). Related: Bordered; bordering.
