- I have found interesting definitions for border and frontier in this etymology dictionary on the web.
- the word Border goes back to 1350, and is derived from an old French word bordure “seam, edge, border”,
- “The geopolitical sense first attested 1535, in Scottish (replacing earlier march), from The Borders, district adjoining the boundary between England and Scotland.”
The synonym of border, boundary appeared around 300 years later, and also has French origins from “Old French bodne, from M.L. bodina, butina “boundary, boundary marker”, perhaps infl. by M.L. bonnarium “piece of land within a fixed limit.”
Frontier: “c.1400, from O.Fr. fronter, from front “brow”. Originally the front line of an army, sense of “borderland” is first attested 1413. In reference to N.Amer., from 1676; later with a specific sense:
“What is the frontier? … In the census reports it is treated as the margin of that settlement which has a density of two or more to the square mile.” [F.J. Turner, “The Frontier in American History”]
Frontiersman is from 1782.
Amazing, that all words for border come from French (through Latin sometimes)