An Etymological Dictionary of the German Language/Pfosten
Pfosten, m., ‘post, stake,’ from MidHG. pfoste, OHG. pfosto, m., ‘post, beam’; comp. Du. post, ‘door-post,’ AS. and E. post; from Lat. postis, the dimin. of which, postellus (Fr. poteau), is preserved in the Rom. languages. The word was borrowed in pre-HG. times contemporaneously with Pfahl.