"ieri l'altro" meaning in Italian

{
  "head_templates": [
    {
      "args": {},
      "expansion": "ieri l'altro",
      "name": "it-adv"
    }
  ],
  "lang": "Italian",
  "lang_code": "it",
  "pos": "adv",
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "Italian 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"
        },
        {
          "kind": "topical",
          "langcode": "it",
          "name": "Time",
          "orig": "it:Time",
          "parents": [
            "All topics",
            "Fundamental"
          ],
          "source": "w"
        }
      ],
      "glosses": [
        "day before yesterday"
      ],
      "id": "en-ieri_l'altro-it-adv-cgxsjAEE",
      "links": [
        [
          "day before yesterday",
          "day before yesterday"
        ]
      ],
      "related": [
        {
          "word": "ieri"
        }
      ],
      "synonyms": [
        {
          "word": "avantieri"
        },
        {
          "word": "l'altro ieri"
        },
        {
          "word": "ierlaltro"
        }
      ]
    }
  ],
  "word": "ieri l'altro"
}

{
  "head_templates": [
    {
      "args": {},
      "expansion": "ieri l'altro",
      "name": "it-adv"
    }
  ],
  "lang": "Italian",
  "lang_code": "it",
  "pos": "adv",
  "related": [
    {
      "word": "ieri"
    }
  ],
  "senses": [
    {
      "categories": [
        "Italian adverbs",
        "Italian entries with incorrect language header",
        "Italian lemmas",
        "Italian multiword terms",
        "Pages with 1 entry",
        "Pages with entries",
        "it:Time"
      ],
      "glosses": [
        "day before yesterday"
      ],
      "links": [
        [
          "day before yesterday",
          "day before yesterday"
        ]
      ],
      "synonyms": [
        {
          "word": "avantieri"
        },
        {
          "word": "l'altro ieri"
        }
      ]
    }
  ],
  "synonyms": [
    {
      "word": "ierlaltro"
    }
  ],
  "word": "ieri l'altro"
}