An Etymological Dictionary of the German Language/Annotated/Elf

by Friedrich Kluge

Elf, masculine, simply Modern High German borrowed in the last century from the equivalent English elf (compare Halle, Heim); also Modern High German Elfe, feminine; for further references see Alp. The Middle High German ęlbe, ęlbinne, feminine, shows that a corresponding Modern High German would have b in place of f.