"slack up" meaning in English

{
  "forms": [
    {
      "form": "slacks up",
      "tags": [
        "present",
        "singular",
        "third-person"
      ]
    },
    {
      "form": "slacking up",
      "tags": [
        "participle",
        "present"
      ]
    },
    {
      "form": "slacked up",
      "tags": [
        "participle",
        "past"
      ]
    },
    {
      "form": "slacked up",
      "tags": [
        "past"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {
        "1": "*"
      },
      "expansion": "slack up (third-person singular simple present slacks up, present participle slacking up, simple past and past participle slacked up)",
      "name": "en-verb"
    },
    {
      "args": {
        "1": "en",
        "2": "idiomatic"
      },
      "expansion": "(idiomatic)",
      "name": "tlb"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "verb",
  "senses": [
    {
      "categories": [],
      "examples": [
        {
          "ref": "1877, Rowland Cox, The American Law Times (volume 4, page 414)",
          "text": "[…] he was rnnning toward the girl; […] he looked right toward her; he slacked up a little, and then started off on a run; don't know whether he saw me or not."
        }
      ],
      "glosses": [
        "To become slack; slacken."
      ],
      "id": "en-slack_up-en-verb-p808XuvV",
      "links": [
        [
          "slacken",
          "slacken"
        ]
      ],
      "raw_glosses": [
        "(intransitive) To become slack; slacken."
      ],
      "tags": [
        "idiomatic",
        "intransitive"
      ]
    },
    {
      "categories": [
        {
          "_dis": "9 91",
          "kind": "other",
          "name": "English entries with incorrect language header",
          "parents": [],
          "source": "w+disamb"
        },
        {
          "_dis": "14 86",
          "kind": "other",
          "name": "English phrasal verbs formed with \"up\"",
          "parents": [],
          "source": "w+disamb"
        },
        {
          "_dis": "7 93",
          "kind": "other",
          "name": "Pages with 1 entry",
          "parents": [],
          "source": "w+disamb"
        },
        {
          "_dis": "6 94",
          "kind": "other",
          "name": "Pages with entries",
          "parents": [],
          "source": "w+disamb"
        }
      ],
      "glosses": [
        "To slack; to let one's standards slip."
      ],
      "id": "en-slack_up-en-verb-iX8ZlHjn",
      "links": [
        [
          "slack",
          "slack"
        ],
        [
          "standards",
          "standards"
        ],
        [
          "slip",
          "slip"
        ]
      ],
      "raw_glosses": [
        "(intransitive) To slack; to let one's standards slip."
      ],
      "tags": [
        "idiomatic",
        "intransitive"
      ]
    }
  ],
  "word": "slack up"
}

{
  "categories": [
    "English entries with incorrect language header",
    "English idioms",
    "English lemmas",
    "English multiword terms",
    "English phrasal verbs",
    "English phrasal verbs formed with \"up\"",
    "English verbs",
    "Pages with 1 entry",
    "Pages with entries"
  ],
  "forms": [
    {
      "form": "slacks up",
      "tags": [
        "present",
        "singular",
        "third-person"
      ]
    },
    {
      "form": "slacking up",
      "tags": [
        "participle",
        "present"
      ]
    },
    {
      "form": "slacked up",
      "tags": [
        "participle",
        "past"
      ]
    },
    {
      "form": "slacked up",
      "tags": [
        "past"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {
        "1": "*"
      },
      "expansion": "slack up (third-person singular simple present slacks up, present participle slacking up, simple past and past participle slacked up)",
      "name": "en-verb"
    },
    {
      "args": {
        "1": "en",
        "2": "idiomatic"
      },
      "expansion": "(idiomatic)",
      "name": "tlb"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "verb",
  "senses": [
    {
      "categories": [
        "English intransitive verbs"
      ],
      "examples": [
        {
          "ref": "1877, Rowland Cox, The American Law Times (volume 4, page 414)",
          "text": "[…] he was rnnning toward the girl; […] he looked right toward her; he slacked up a little, and then started off on a run; don't know whether he saw me or not."
        }
      ],
      "glosses": [
        "To become slack; slacken."
      ],
      "links": [
        [
          "slacken",
          "slacken"
        ]
      ],
      "raw_glosses": [
        "(intransitive) To become slack; slacken."
      ],
      "tags": [
        "idiomatic",
        "intransitive"
      ]
    },
    {
      "categories": [
        "English intransitive verbs"
      ],
      "glosses": [
        "To slack; to let one's standards slip."
      ],
      "links": [
        [
          "slack",
          "slack"
        ],
        [
          "standards",
          "standards"
        ],
        [
          "slip",
          "slip"
        ]
      ],
      "raw_glosses": [
        "(intransitive) To slack; to let one's standards slip."
      ],
      "tags": [
        "idiomatic",
        "intransitive"
      ]
    }
  ],
  "word": "slack up"
}