"side of ship," O.E.
bord "border, rim, ship's side," from P.Gmc.
*bordaz (cf. O.S.
bord, Du.
boord, Ger.
Bord, O.H.G.
bart, O.N.
barð), perhaps from PIE
*bhrtos "raised, made projecting." Connected to
border. See also
starboard. Under this theory, etymologically not related to
board (1), but the two forms represented in English by these words were more or less confused at an early date in most Germanic languages, a situation made worse in English because this Germanic root also was adopted as M.L.
bordus (cf. It. and Sp.
bordo). It also entered O.Fr. as
bort "beam, board, plank; side of a ship" (12c., Mod.Fr.
bord), either from M.L. or Frankish, and from thence it came over with the Normans to mingle with its native cousins. By now the senses are inextricably tangled. Some etymology dictionaries treat them as having been the same word all along.