dop·pel·gäng·er or dop·pel·gang·er (dŏp'əl-găng'ər, -gĕng'-)

n. A ghostly double of a living person, especially one that haunts its fleshly counterpart.

[German, a double : doppel, double (from French double; see double) + Gänger, goer (from Gang, a going, from Middle High German ganc, from Old High German).]

[The American Heritage® Dictionary of the English Language, Fourth Edition]

Footnote: I remember first coming upon the word doppelgänger in Konami's 1990 NES release Castlevania III: Dracula's Curse. Great game!

Labels: German, Middle High German, Old High German, The Daily Hump