"yr undydd" meaning in Welsh

{
  "etymology_templates": [
    {
      "args": {
        "1": "cy",
        "2": "yr",
        "3": "",
        "4": "the"
      },
      "expansion": "yr (“the”)",
      "name": "l"
    },
    {
      "args": {
        "1": "cy",
        "2": "undydd",
        "3": "",
        "4": "one day"
      },
      "expansion": "undydd (“one day”)",
      "name": "l"
    }
  ],
  "etymology_text": "yr (“the”) + undydd (“one day”).",
  "head_templates": [
    {
      "args": {
        "1": "m",
        "2": "-"
      },
      "expansion": "yr undydd m (uncountable)",
      "name": "cy-noun"
    }
  ],
  "lang": "Welsh",
  "lang_code": "cy",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "Welsh entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
          ],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Welsh links with redundant wikilinks",
          "parents": [
            "Links with redundant wikilinks",
            "Entry maintenance"
          ],
          "source": "w"
        },
        {
          "kind": "topical",
          "langcode": "cy",
          "name": "Time",
          "orig": "cy:Time",
          "parents": [
            "All topics",
            "Fundamental"
          ],
          "source": "w"
        }
      ],
      "glosses": [
        "the same day"
      ],
      "id": "en-yr_undydd-cy-noun-Y1GcrTCa",
      "links": [
        [
          "same",
          "same"
        ],
        [
          "day",
          "day"
        ]
      ],
      "raw_glosses": [
        "(idiomatic) the same day"
      ],
      "related": [
        {
          "english": "the same night",
          "word": "yr unnos"
        }
      ],
      "tags": [
        "idiomatic",
        "masculine",
        "uncountable"
      ]
    }
  ],
  "sounds": [
    {
      "ipa": "/əˈrɨ̞ndɨ̞ð/",
      "tags": [
        "North-Wales"
      ]
    },
    {
      "ipa": "/əˈrɪndɪð/",
      "tags": [
        "South-Wales"
      ]
    },
    {
      "rhymes": "-ɨ̞ndɨ̞ð"
    }
  ],
  "word": "yr undydd"
}

{
  "etymology_templates": [
    {
      "args": {
        "1": "cy",
        "2": "yr",
        "3": "",
        "4": "the"
      },
      "expansion": "yr (“the”)",
      "name": "l"
    },
    {
      "args": {
        "1": "cy",
        "2": "undydd",
        "3": "",
        "4": "one day"
      },
      "expansion": "undydd (“one day”)",
      "name": "l"
    }
  ],
  "etymology_text": "yr (“the”) + undydd (“one day”).",
  "head_templates": [
    {
      "args": {
        "1": "m",
        "2": "-"
      },
      "expansion": "yr undydd m (uncountable)",
      "name": "cy-noun"
    }
  ],
  "lang": "Welsh",
  "lang_code": "cy",
  "pos": "noun",
  "related": [
    {
      "english": "the same night",
      "word": "yr unnos"
    }
  ],
  "senses": [
    {
      "categories": [
        "Rhymes:Welsh/ɨ̞ndɨ̞ð",
        "Rhymes:Welsh/ɨ̞ndɨ̞ð/3 syllables",
        "Welsh entries with incorrect language header",
        "Welsh idioms",
        "Welsh lemmas",
        "Welsh links with redundant wikilinks",
        "Welsh masculine nouns",
        "Welsh multiword terms",
        "Welsh nouns",
        "Welsh terms with IPA pronunciation",
        "Welsh uncountable nouns",
        "cy:Time"
      ],
      "glosses": [
        "the same day"
      ],
      "links": [
        [
          "same",
          "same"
        ],
        [
          "day",
          "day"
        ]
      ],
      "raw_glosses": [
        "(idiomatic) the same day"
      ],
      "tags": [
        "idiomatic",
        "masculine",
        "uncountable"
      ]
    }
  ],
  "sounds": [
    {
      "ipa": "/əˈrɨ̞ndɨ̞ð/",
      "tags": [
        "North-Wales"
      ]
    },
    {
      "ipa": "/əˈrɪndɪð/",
      "tags": [
        "South-Wales"
      ]
    },
    {
      "rhymes": "-ɨ̞ndɨ̞ð"
    }
  ],
  "word": "yr undydd"
}