"X mark" meaning in English

{
  "antonyms": [
    {
      "alt": "✓",
      "word": "checkmark"
    },
    {
      "alt": "◯",
      "english": "used in Japanese",
      "word": "O mark"
    }
  ],
  "forms": [
    {
      "form": "X marks",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "X mark (plural X marks)",
      "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": "other",
          "name": "Pages with 1 entry",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Pages with entries",
          "parents": [],
          "source": "w"
        }
      ],
      "glosses": [
        "A symbol composed of two perpendicular lines (✗), especially when representing negation or lack of verification."
      ],
      "id": "en-X_mark-en-noun-Gigx-B-V",
      "links": [
        [
          "symbol",
          "symbol"
        ],
        [
          "perpendicular",
          "perpendicular"
        ],
        [
          "✗",
          "✗"
        ],
        [
          "negation",
          "negation"
        ],
        [
          "verification",
          "verification"
        ]
      ]
    }
  ],
  "word": "X mark"
}

{
  "antonyms": [
    {
      "alt": "✓",
      "word": "checkmark"
    },
    {
      "alt": "◯",
      "english": "used in Japanese",
      "word": "O mark"
    }
  ],
  "forms": [
    {
      "form": "X marks",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "X mark (plural X marks)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        "English countable nouns",
        "English entries with incorrect language header",
        "English lemmas",
        "English multiword terms",
        "English nouns",
        "English terms derived from the shape of letters",
        "Pages with 1 entry",
        "Pages with entries"
      ],
      "glosses": [
        "A symbol composed of two perpendicular lines (✗), especially when representing negation or lack of verification."
      ],
      "links": [
        [
          "symbol",
          "symbol"
        ],
        [
          "perpendicular",
          "perpendicular"
        ],
        [
          "✗",
          "✗"
        ],
        [
          "negation",
          "negation"
        ],
        [
          "verification",
          "verification"
        ]
      ]
    }
  ],
  "word": "X mark"
}