"non-detection" meaning in English

{
  "forms": [
    {
      "form": "non-detections",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {
        "1": "~"
      },
      "expansion": "non-detection (countable and uncountable, plural non-detections)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "alt_of": [
        {
          "word": "nondetection"
        }
      ],
      "categories": [
        {
          "kind": "other",
          "name": "English entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
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          "source": "w"
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      "examples": [
        {
          "ref": "2006 August, Alexander V. Krivov, Artem G. Feofilov, Valeri V. Dikarev, “Search for the putative dust belts of Mars: The late 2007 opportunity”, in Planetary and Space Science, volume 54, numbers 9–10, →DOI, page 871",
          "text": "This paper analyzes possible reasons for non-detection of the belts and focuses on the next, and the last for three decades to come, natural opportunity to search for the dust belts during the Mars ring plane crossing in December 2007.",
          "type": "quotation"
        }
      ],
      "glosses": [
        "Alternative form of nondetection."
      ],
      "id": "en-non-detection-en-noun-5HDNQACQ",
      "links": [
        [
          "nondetection",
          "nondetection#English"
        ]
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      "tags": [
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    }
  ],
  "word": "non-detection"
}

{
  "forms": [
    {
      "form": "non-detections",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {
        "1": "~"
      },
      "expansion": "non-detection (countable and uncountable, plural non-detections)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "alt_of": [
        {
          "word": "nondetection"
        }
      ],
      "categories": [
        "English countable nouns",
        "English entries with incorrect language header",
        "English lemmas",
        "English multiword terms",
        "English nouns",
        "English terms with quotations",
        "English uncountable nouns"
      ],
      "examples": [
        {
          "ref": "2006 August, Alexander V. Krivov, Artem G. Feofilov, Valeri V. Dikarev, “Search for the putative dust belts of Mars: The late 2007 opportunity”, in Planetary and Space Science, volume 54, numbers 9–10, →DOI, page 871",
          "text": "This paper analyzes possible reasons for non-detection of the belts and focuses on the next, and the last for three decades to come, natural opportunity to search for the dust belts during the Mars ring plane crossing in December 2007.",
          "type": "quotation"
        }
      ],
      "glosses": [
        "Alternative form of nondetection."
      ],
      "links": [
        [
          "nondetection",
          "nondetection#English"
        ]
      ],
      "tags": [
        "alt-of",
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    }
  ],
  "word": "non-detection"
}