"a Roland for an Oliver" meaning in English

{
  "etymology_text": "From the stories of Roland and Oliver, legendary knights of equal might.",
  "forms": [
    {
      "form": "Rolands for Olivers",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {
        "1": "Rolands for Olivers"
      },
      "expansion": "a Roland for an Oliver (plural Rolands for Olivers)",
      "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": "English entries with language name categories using raw markup",
          "parents": [
            "Entries with language name categories using raw markup",
            "Entry maintenance"
          ],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "English terms with non-redundant non-automated sortkeys",
          "parents": [
            "Terms with non-redundant non-automated sortkeys",
            "Entry maintenance"
          ],
          "source": "w"
        }
      ],
      "glosses": [
        "Equal measure; measure for measure; adequate response."
      ],
      "id": "en-a_Roland_for_an_Oliver-en-noun-hv9l2E4M",
      "links": [
        [
          "Equal",
          "equal"
        ],
        [
          "measure for measure",
          "measure for measure"
        ],
        [
          "adequate",
          "adequate"
        ],
        [
          "response",
          "response"
        ]
      ],
      "raw_glosses": [
        "(idiomatic) Equal measure; measure for measure; adequate response."
      ],
      "synonyms": [
        {
          "word": "eye for an eye"
        },
        {
          "word": "tit for tat"
        }
      ],
      "tags": [
        "idiomatic"
      ]
    }
  ],
  "word": "a Roland for an Oliver"
}

{
  "etymology_text": "From the stories of Roland and Oliver, legendary knights of equal might.",
  "forms": [
    {
      "form": "Rolands for Olivers",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {
        "1": "Rolands for Olivers"
      },
      "expansion": "a Roland for an Oliver (plural Rolands for Olivers)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        "English countable nouns",
        "English entries with incorrect language header",
        "English entries with language name categories using raw markup",
        "English eponyms",
        "English idioms",
        "English lemmas",
        "English multiword terms",
        "English nouns",
        "English terms with non-redundant non-automated sortkeys"
      ],
      "glosses": [
        "Equal measure; measure for measure; adequate response."
      ],
      "links": [
        [
          "Equal",
          "equal"
        ],
        [
          "measure for measure",
          "measure for measure"
        ],
        [
          "adequate",
          "adequate"
        ],
        [
          "response",
          "response"
        ]
      ],
      "raw_glosses": [
        "(idiomatic) Equal measure; measure for measure; adequate response."
      ],
      "tags": [
        "idiomatic"
      ]
    }
  ],
  "synonyms": [
    {
      "word": "eye for an eye"
    },
    {
      "word": "tit for tat"
    }
  ],
  "word": "a Roland for an Oliver"
}