"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"
        },
        {
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          "name": "English entries with incorrect language header",
          "parents": [
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          "source": "w"
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          "name": "English negative polarity items",
          "parents": [
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            "Terms by semantic function"
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          "source": "w"
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          "kind": "other",
          "name": "English predicates",
          "parents": [],
          "source": "w"
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          "source": "w"
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        }
      ],
      "examples": [
        {
          "text": "If the train had come just five seconds earlier... well, it just doesn't bear thinking about!",
          "type": "example"
        }
      ],
      "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 lemmas",
        "English multiword terms",
        "English negative polarity items",
        "English predicates",
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        "English verbs",
        "Pages with 1 entry",
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      ],
      "examples": [
        {
          "text": "If the train had come just five seconds earlier... well, it just doesn't bear thinking about!",
          "type": "example"
        }
      ],
      "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"
}