"zero line" meaning in English

{
  "forms": [
    {
      "form": "zero lines",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "zero line (plural zero lines)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "English entries with incorrect language header",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Entries with translation boxes",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Pages with 1 entry",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Pages with entries",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Terms with Russian translations",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "langcode": "en",
          "name": "War",
          "orig": "en:War",
          "parents": [],
          "source": "w"
        }
      ],
      "examples": [
        {
          "bold_text_offsets": [
            [
              100,
              109
            ]
          ],
          "ref": "2023 March 18, “The Forgotten Villages of Ukraine's 'Zero Line'”, in Rolling Stone:",
          "text": "Outside of the main roads and major cities, life in small-town Ukraine rides a razor's edge on the “zero line” where two armies collide.",
          "type": "quotation"
        },
        {
          "bold_text_offsets": [
            [
              30,
              39
            ]
          ],
          "ref": "2023 April 11, “'They crawl forward 24/7:' On the zero line with Ukrainian infantry north of Bakhmut”, in The Kyiv Independent:",
          "text": "Half an hour's drive from the zero line, an unassuming village house marks an important landmark for those unfortunate enough to need to […]",
          "type": "quotation"
        }
      ],
      "glosses": [
        "The very front of the front line, where opposing armed forces meet and engage in direct combat, especially the border between (US forces in) Afghanistan and Pakistan, or between Ukrainian and Russian forces."
      ],
      "id": "en-zero_line-en-noun-DIlbjLeP",
      "links": [
        [
          "front",
          "front"
        ],
        [
          "front line",
          "front line"
        ],
        [
          "direct",
          "direct"
        ],
        [
          "combat",
          "combat"
        ]
      ],
      "translations": [
        {
          "code": "ru",
          "lang": "Russian",
          "lang_code": "ru",
          "roman": "nulevája línija",
          "sense": "the very front of the front line",
          "tags": [
            "feminine"
          ],
          "word": "нулева́я ли́ния"
        },
        {
          "code": "ru",
          "lang": "Russian",
          "lang_code": "ru",
          "roman": "nolʹ",
          "sense": "the very front of the front line",
          "tags": [
            "masculine",
            "slang"
          ],
          "word": "ноль"
        },
        {
          "code": "ru",
          "lang": "Russian",
          "lang_code": "ru",
          "roman": "nulʹ",
          "sense": "the very front of the front line",
          "tags": [
            "masculine",
            "slang"
          ],
          "word": "нуль"
        }
      ]
    }
  ],
  "word": "zero line"
}

{
  "forms": [
    {
      "form": "zero lines",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "zero line (plural zero lines)",
      "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 with quotations",
        "Entries with translation boxes",
        "Pages with 1 entry",
        "Pages with entries",
        "Terms with Russian translations",
        "en:War"
      ],
      "examples": [
        {
          "bold_text_offsets": [
            [
              100,
              109
            ]
          ],
          "ref": "2023 March 18, “The Forgotten Villages of Ukraine's 'Zero Line'”, in Rolling Stone:",
          "text": "Outside of the main roads and major cities, life in small-town Ukraine rides a razor's edge on the “zero line” where two armies collide.",
          "type": "quotation"
        },
        {
          "bold_text_offsets": [
            [
              30,
              39
            ]
          ],
          "ref": "2023 April 11, “'They crawl forward 24/7:' On the zero line with Ukrainian infantry north of Bakhmut”, in The Kyiv Independent:",
          "text": "Half an hour's drive from the zero line, an unassuming village house marks an important landmark for those unfortunate enough to need to […]",
          "type": "quotation"
        }
      ],
      "glosses": [
        "The very front of the front line, where opposing armed forces meet and engage in direct combat, especially the border between (US forces in) Afghanistan and Pakistan, or between Ukrainian and Russian forces."
      ],
      "links": [
        [
          "front",
          "front"
        ],
        [
          "front line",
          "front line"
        ],
        [
          "direct",
          "direct"
        ],
        [
          "combat",
          "combat"
        ]
      ]
    }
  ],
  "translations": [
    {
      "code": "ru",
      "lang": "Russian",
      "lang_code": "ru",
      "roman": "nulevája línija",
      "sense": "the very front of the front line",
      "tags": [
        "feminine"
      ],
      "word": "нулева́я ли́ния"
    },
    {
      "code": "ru",
      "lang": "Russian",
      "lang_code": "ru",
      "roman": "nolʹ",
      "sense": "the very front of the front line",
      "tags": [
        "masculine",
        "slang"
      ],
      "word": "ноль"
    },
    {
      "code": "ru",
      "lang": "Russian",
      "lang_code": "ru",
      "roman": "nulʹ",
      "sense": "the very front of the front line",
      "tags": [
        "masculine",
        "slang"
      ],
      "word": "нуль"
    }
  ],
  "word": "zero line"
}