From Germanic 'Nixe,' a water sprite or mermaid of folklore.
Nixie springs from the deep wells of Germanic and Scandinavian folklore, where the Nix (German: Nixe for the female form) was a shapeshifting water spirit inhabiting rivers, lakes, and streams. These beings — sometimes beautiful, sometimes terrifying — could appear as human, horse, or fish-tailed creature, and their encounters with mortals often carried the bittersweet charge of all fairy-tale crossings between worlds. The word itself traces to Old High German "nihhus" and is cognate with Old English "nicor," the very creature mentioned in Beowulf when the hero battles the monsters in the mere.
Wagner's opera "Das Rheingold" and Undine myths draw on the same reservoir of water-spirit lore. As a given name rather than a creature type, Nixie has functioned both as a standalone name and as a diminutive — of Nicole, Nix, or other Ni- names — with the same logic that turns Alexandra into Lexi or Beatrice into Bea. In this diminutive register, Nixie is playful and bright, its terminal "ie" lending it the warmth of a childhood nickname made permanent.
The name also appears in mid-twentieth century American slang as a term for a postal letter that cannot be delivered — a small, forgotten ghost of a meaning that adds a wistful quality to its history. In the contemporary naming landscape, Nixie fits beautifully into the growing appetite for mythological names with fairy-tale resonance — alongside Seren, Ondine, and Melusine — while its brevity and familiar sound make it genuinely wearable. It is a name that feels both ancient and impossibly fresh.