"negative lookbehind" meaning in English

{
  "etymology_templates": [
    {
      "args": {
        "1": "en",
        "2": "negative",
        "3": "lookbehind"
      },
      "expansion": "negative + lookbehind",
      "name": "compound"
    }
  ],
  "etymology_text": "negative + lookbehind",
  "forms": [
    {
      "form": "negative lookbehinds",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {
        "1": "~"
      },
      "expansion": "negative lookbehind (countable and uncountable, plural negative lookbehinds)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "English entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
          ],
          "source": "w"
        },
        {
          "kind": "topical",
          "langcode": "en",
          "name": "Regular expressions",
          "orig": "en:Regular expressions",
          "parents": [
            "Computing",
            "Programming",
            "Technology",
            "Software engineering",
            "All topics",
            "Computer science",
            "Engineering",
            "Software",
            "Fundamental",
            "Sciences",
            "Applied sciences",
            "Media",
            "Communication"
          ],
          "source": "w"
        }
      ],
      "glosses": [
        "The analysis of the preceding characters absence before the regular expression is matched (symbol: ?<!)."
      ],
      "hypernyms": [
        {
          "sense": "lookaround",
          "word": "lookbehind"
        }
      ],
      "id": "en-negative_lookbehind-en-noun-A~wX8FRE",
      "links": [
        [
          "regular expression",
          "regular expression"
        ],
        [
          "analysis",
          "analysis"
        ],
        [
          "character",
          "character"
        ]
      ],
      "qualifier": "regular expressions",
      "raw_glosses": [
        "(regular expressions) The analysis of the preceding characters absence before the regular expression is matched (symbol: ?<!)."
      ],
      "tags": [
        "countable",
        "uncountable"
      ]
    }
  ],
  "word": "negative lookbehind"
}

{
  "etymology_templates": [
    {
      "args": {
        "1": "en",
        "2": "negative",
        "3": "lookbehind"
      },
      "expansion": "negative + lookbehind",
      "name": "compound"
    }
  ],
  "etymology_text": "negative + lookbehind",
  "forms": [
    {
      "form": "negative lookbehinds",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {
        "1": "~"
      },
      "expansion": "negative lookbehind (countable and uncountable, plural negative lookbehinds)",
      "name": "en-noun"
    }
  ],
  "hypernyms": [
    {
      "sense": "lookaround",
      "word": "lookbehind"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        "English compound terms",
        "English countable nouns",
        "English entries with incorrect language header",
        "English lemmas",
        "English multiword terms",
        "English nouns",
        "English uncountable nouns",
        "en:Regular expressions"
      ],
      "glosses": [
        "The analysis of the preceding characters absence before the regular expression is matched (symbol: ?<!)."
      ],
      "links": [
        [
          "regular expression",
          "regular expression"
        ],
        [
          "analysis",
          "analysis"
        ],
        [
          "character",
          "character"
        ]
      ],
      "qualifier": "regular expressions",
      "raw_glosses": [
        "(regular expressions) The analysis of the preceding characters absence before the regular expression is matched (symbol: ?<!)."
      ],
      "tags": [
        "countable",
        "uncountable"
      ]
    }
  ],
  "word": "negative lookbehind"
}