"foo fighter" meaning in English

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  "etymology_text": "From foo, either a nonce word or a corruption of the French word feu (“fire”), + fighter (“type of aircraft”).",
  "forms": [
    {
      "form": "foo fighters",
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  "lang_code": "en",
  "pos": "noun",
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      "glosses": [
        "Any of various unidentified flying objects, as reported by Allied pilots during World War II."
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        "foo fighter"
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  "word": "foo fighter"
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  "etymology_text": "From foo, either a nonce word or a corruption of the French word feu (“fire”), + fighter (“type of aircraft”).",
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    {
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      "tags": [
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