"plainhead" meaning in English

{
  "etymology_templates": [
    {
      "args": {
        "1": "en",
        "2": "plain",
        "3": "head"
      },
      "expansion": "plain + head",
      "name": "compound"
    }
  ],
  "etymology_text": "From plain + head.",
  "forms": [
    {
      "form": "plainheads",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "plainhead (plural plainheads)",
      "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": "Pages with 1 entry",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Pages with entries",
          "parents": [],
          "source": "w"
        }
      ],
      "derived": [
        {
          "word": "Australian plainhead"
        },
        {
          "word": "Norwich plainhead"
        }
      ],
      "glosses": [
        "A variety of bird without a crest."
      ],
      "id": "en-plainhead-en-noun-e0MqcyPA",
      "links": [
        [
          "bird",
          "bird"
        ],
        [
          "crest",
          "crest"
        ]
      ]
    }
  ],
  "word": "plainhead"
}

{
  "derived": [
    {
      "word": "Australian plainhead"
    },
    {
      "word": "Norwich plainhead"
    }
  ],
  "etymology_templates": [
    {
      "args": {
        "1": "en",
        "2": "plain",
        "3": "head"
      },
      "expansion": "plain + head",
      "name": "compound"
    }
  ],
  "etymology_text": "From plain + head.",
  "forms": [
    {
      "form": "plainheads",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "plainhead (plural plainheads)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        "English compound terms",
        "English countable nouns",
        "English entries with incorrect language header",
        "English lemmas",
        "English nouns",
        "Pages with 1 entry",
        "Pages with entries"
      ],
      "glosses": [
        "A variety of bird without a crest."
      ],
      "links": [
        [
          "bird",
          "bird"
        ],
        [
          "crest",
          "crest"
        ]
      ]
    }
  ],
  "word": "plainhead"
}