"of a" meaning in English

{
  "head_templates": [
    {
      "args": {
        "1": "en",
        "2": "phrase"
      },
      "expansion": "of a",
      "name": "head"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "phrase",
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "English entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
          ],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "English non-constituents",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Pages with 1 entry",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Pages with entries",
          "parents": [],
          "source": "w"
        }
      ],
      "examples": [
        {
          "ref": "1839, John Gibson Lockhart, Memoirs of the Life of Sir Walter Scott, Bart:",
          "text": "He always used to dine at my father's house of a Sunday.",
          "type": "quote"
        },
        {
          "ref": "2008, Kim Patrick, Rewarding Good Behavior in Children:",
          "text": "So, next time they come to me of a morning and ask the same question, what do you think my answer might be?",
          "type": "quote"
        }
      ],
      "glosses": [
        "on every; in the (followed by a noun indicating a certain time)"
      ],
      "id": "en-of_a-en-phrase-909W~FGE",
      "links": [
        [
          "on",
          "on"
        ],
        [
          "every",
          "every"
        ]
      ],
      "raw_glosses": [
        "(dated, now dialectal, idiomatic) on every; in the (followed by a noun indicating a certain time)"
      ],
      "related": [
        {
          "word": "of an"
        }
      ],
      "tags": [
        "dated",
        "dialectal",
        "idiomatic"
      ]
    }
  ],
  "sounds": [
    {
      "audio": "En-au-of a.ogg",
      "mp3_url": "https://upload.wikimedia.org/wikipedia/commons/transcoded/8/87/En-au-of_a.ogg/En-au-of_a.ogg.mp3",
      "ogg_url": "https://upload.wikimedia.org/wikipedia/commons/8/87/En-au-of_a.ogg"
    }
  ],
  "word": "of a"
}

{
  "head_templates": [
    {
      "args": {
        "1": "en",
        "2": "phrase"
      },
      "expansion": "of a",
      "name": "head"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "phrase",
  "related": [
    {
      "word": "of an"
    }
  ],
  "senses": [
    {
      "categories": [
        "English dated terms",
        "English dialectal terms",
        "English entries with incorrect language header",
        "English idioms",
        "English lemmas",
        "English multiword terms",
        "English non-constituents",
        "English phrases",
        "English terms with quotations",
        "Pages with 1 entry",
        "Pages with entries",
        "Quotation templates to be cleaned"
      ],
      "examples": [
        {
          "ref": "1839, John Gibson Lockhart, Memoirs of the Life of Sir Walter Scott, Bart:",
          "text": "He always used to dine at my father's house of a Sunday.",
          "type": "quote"
        },
        {
          "ref": "2008, Kim Patrick, Rewarding Good Behavior in Children:",
          "text": "So, next time they come to me of a morning and ask the same question, what do you think my answer might be?",
          "type": "quote"
        }
      ],
      "glosses": [
        "on every; in the (followed by a noun indicating a certain time)"
      ],
      "links": [
        [
          "on",
          "on"
        ],
        [
          "every",
          "every"
        ]
      ],
      "raw_glosses": [
        "(dated, now dialectal, idiomatic) on every; in the (followed by a noun indicating a certain time)"
      ],
      "tags": [
        "dated",
        "dialectal",
        "idiomatic"
      ]
    }
  ],
  "sounds": [
    {
      "audio": "En-au-of a.ogg",
      "mp3_url": "https://upload.wikimedia.org/wikipedia/commons/transcoded/8/87/En-au-of_a.ogg/En-au-of_a.ogg.mp3",
      "ogg_url": "https://upload.wikimedia.org/wikipedia/commons/8/87/En-au-of_a.ogg"
    }
  ],
  "word": "of a"
}