Answer:
How did the term “seaboard” come to be a synonym for “seacoast”?
A: In Old English, the language spoken in Anglo-Saxon times, the term bord (the source of our modern word “board”) had two meanings: (1) a plank, shield, shelf, or table; and (2) an edge, rim, or side.
The second meaning dates back at least to the year 897, and it’s this sense that gives us the words “border” and “seaboard” (meaning seaside, seacoast, seashore).
This meaning of “board” as an edge or side also gave us the words “shipboard” (the side of a ship) and “overboard” (over the side of a ship), as well as “larboard” and “starboard.”
When the phrase “on board” first appeared in English in the early 16th century, it meant alongside a ship (or a shore), but the meaning widened by the late 17th century to include on a ship itself.
Other old nautical expressions reflecting this etymology included “board on board” and “board by board,” which described two ships coming alongside one another (side by side).
It’s often supposed that the “board” in “on board” refers to the deck of a ship, according to the Oxford English Dictionary, but the Middle English version of the expression, within schippe burdez (“within ship boards”), makes clear the word “board” actually refers to a border.
The OED says the two Anglo-Saxon meanings of bord (a plank and an edge) may have been the result of entirely different nouns from different sources, already blended by the time they arrived in Old English.
