"grass up" meaning in English

{
  "etymology_text": "From grass (“informer”) + up.",
  "forms": [
    {
      "form": "grasses up",
      "tags": [
        "present",
        "singular",
        "third-person"
      ]
    },
    {
      "form": "grassing up",
      "tags": [
        "participle",
        "present"
      ]
    },
    {
      "form": "grassed up",
      "tags": [
        "participle",
        "past"
      ]
    },
    {
      "form": "grassed up",
      "tags": [
        "past"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {
        "1": "*"
      },
      "expansion": "grass up (third-person singular simple present grasses up, present participle grassing up, simple past and past participle grassed up)",
      "name": "en-verb"
    }
  ],
  "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"
          ],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "English phrasal verbs formed with \"up\"",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Pages with 1 entry",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Pages with entries",
          "parents": [],
          "source": "w"
        }
      ],
      "examples": [
        {
          "ref": "1999, Angela Devlin, Bob Turney, Going Straight: After Crime and Punishment, →ISBN:",
          "text": "My sister grassed me up to the caretaker! She thought she was doing me a favour — by grassing me up she was sure he'd let me off.",
          "type": "quote"
        }
      ],
      "glosses": [
        "To betray by informing on."
      ],
      "id": "en-grass_up-en-verb-~KO4hGeC",
      "links": [
        [
          "betray",
          "betray"
        ],
        [
          "informing on",
          "informant"
        ]
      ],
      "raw_glosses": [
        "(UK, slang) To betray by informing on."
      ],
      "related": [
        {
          "word": "supergrass"
        }
      ],
      "synonyms": [
        {
          "word": "drop a dime"
        },
        {
          "word": "name names"
        },
        {
          "word": "snitch"
        }
      ],
      "tags": [
        "UK",
        "slang"
      ]
    }
  ],
  "sounds": [
    {
      "audio": "En-au-grass up.ogg",
      "mp3_url": "https://upload.wikimedia.org/wikipedia/commons/transcoded/3/34/En-au-grass_up.ogg/En-au-grass_up.ogg.mp3",
      "ogg_url": "https://upload.wikimedia.org/wikipedia/commons/3/34/En-au-grass_up.ogg"
    }
  ],
  "word": "grass up"
}

{
  "etymology_text": "From grass (“informer”) + up.",
  "forms": [
    {
      "form": "grasses up",
      "tags": [
        "present",
        "singular",
        "third-person"
      ]
    },
    {
      "form": "grassing up",
      "tags": [
        "participle",
        "present"
      ]
    },
    {
      "form": "grassed up",
      "tags": [
        "participle",
        "past"
      ]
    },
    {
      "form": "grassed up",
      "tags": [
        "past"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {
        "1": "*"
      },
      "expansion": "grass up (third-person singular simple present grasses up, present participle grassing up, simple past and past participle grassed up)",
      "name": "en-verb"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "verb",
  "related": [
    {
      "word": "supergrass"
    }
  ],
  "senses": [
    {
      "categories": [
        "British English",
        "English entries with incorrect language header",
        "English lemmas",
        "English multiword terms",
        "English phrasal verbs",
        "English phrasal verbs formed with \"up\"",
        "English slang",
        "English terms with quotations",
        "English verbs",
        "Pages with 1 entry",
        "Pages with entries"
      ],
      "examples": [
        {
          "ref": "1999, Angela Devlin, Bob Turney, Going Straight: After Crime and Punishment, →ISBN:",
          "text": "My sister grassed me up to the caretaker! She thought she was doing me a favour — by grassing me up she was sure he'd let me off.",
          "type": "quote"
        }
      ],
      "glosses": [
        "To betray by informing on."
      ],
      "links": [
        [
          "betray",
          "betray"
        ],
        [
          "informing on",
          "informant"
        ]
      ],
      "raw_glosses": [
        "(UK, slang) To betray by informing on."
      ],
      "tags": [
        "UK",
        "slang"
      ]
    }
  ],
  "sounds": [
    {
      "audio": "En-au-grass up.ogg",
      "mp3_url": "https://upload.wikimedia.org/wikipedia/commons/transcoded/3/34/En-au-grass_up.ogg/En-au-grass_up.ogg.mp3",
      "ogg_url": "https://upload.wikimedia.org/wikipedia/commons/3/34/En-au-grass_up.ogg"
    }
  ],
  "synonyms": [
    {
      "word": "drop a dime"
    },
    {
      "word": "name names"
    },
    {
      "word": "snitch"
    }
  ],
  "word": "grass up"
}