"not bear thinking about" meaning in English

{
  "head_templates": [
    {
      "args": {
        "1": "en",
        "2": "verb",
        "head": "not bear thinking about"
      },
      "expansion": "not bear thinking about",
      "name": "head"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "verb",
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "British English",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "English entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
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          "source": "w"
        },
        {
          "kind": "other",
          "name": "English entries with language name categories using raw markup",
          "parents": [
            "Entries with language name categories using raw markup",
            "Entry maintenance"
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          "source": "w"
        },
        {
          "kind": "other",
          "name": "English negative polarity items",
          "parents": [
            "Negative polarity items",
            "Terms by semantic function"
          ],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "English predicates",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "English terms with non-redundant non-automated sortkeys",
          "parents": [
            "Terms with non-redundant non-automated sortkeys",
            "Entry maintenance"
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          "source": "w"
        }
      ],
      "examples": [
        {
          "text": "If the train had come just five seconds earlier... well, it just doesn't bear thinking about!"
        }
      ],
      "glosses": [
        "To be too frightening or upsetting to even contemplate."
      ],
      "id": "en-not_bear_thinking_about-en-verb-nCOks7S2",
      "links": [
        [
          "frightening",
          "frightening"
        ],
        [
          "upsetting",
          "upsetting"
        ]
      ],
      "raw_glosses": [
        "(UK) To be too frightening or upsetting to even contemplate."
      ],
      "tags": [
        "UK"
      ]
    }
  ],
  "word": "not bear thinking about"
}

{
  "head_templates": [
    {
      "args": {
        "1": "en",
        "2": "verb",
        "head": "not bear thinking about"
      },
      "expansion": "not bear thinking about",
      "name": "head"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "verb",
  "senses": [
    {
      "categories": [
        "British English",
        "English entries with incorrect language header",
        "English entries with language name categories using raw markup",
        "English lemmas",
        "English multiword terms",
        "English negative polarity items",
        "English predicates",
        "English terms with non-redundant non-automated sortkeys",
        "English verbs"
      ],
      "examples": [
        {
          "text": "If the train had come just five seconds earlier... well, it just doesn't bear thinking about!"
        }
      ],
      "glosses": [
        "To be too frightening or upsetting to even contemplate."
      ],
      "links": [
        [
          "frightening",
          "frightening"
        ],
        [
          "upsetting",
          "upsetting"
        ]
      ],
      "raw_glosses": [
        "(UK) To be too frightening or upsetting to even contemplate."
      ],
      "tags": [
        "UK"
      ]
    }
  ],
  "word": "not bear thinking about"
}