Английский Этимологический словарь - file (n1)

- "line or row," 1598, from M.Fr. file "row," from filer "spin out (thread), march in file," from L.L. filare "to spin, draw out in a long line," from L. filum "thread." Documents hung up on a line like drying laundry. Methods have become more sophisticated, but the word has stuck. Eng. acquired the "military column" sense of the Fr. word late 16c.