Wikipedia
Mannaz
See Man (word) for the Germanic etymology. See Mannus for the mythological ancestor recorded by Tacitus.
*Mannaz is the conventional name of the m- rune of the Elder Futhark. It is derived from the reconstructed Common Germanic word for "man", *mannaz.
Younger Futhark ᛘ is maðr (" man"). It took up the shape of the algiz rune ᛉ, replacing Elder Futhark .
As its sound value and form in the Elder Futhark indicate, it is derived from the letter M in the Old Italic alphabets, ultimately from the Greek letter Mu .