"ultrathin" meaning in English

{
  "etymology_templates": [
    {
      "args": {
        "1": "en",
        "2": "ultra",
        "3": "thin"
      },
      "expansion": "ultra- + thin",
      "name": "prefix"
    }
  ],
  "etymology_text": "ultra- + thin",
  "head_templates": [
    {
      "args": {
        "1": "-"
      },
      "expansion": "ultrathin (not comparable)",
      "name": "en-adj"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "adj",
  "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 terms prefixed with ultra-",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Greek terms with redundant script codes",
          "parents": [
            "Terms with redundant script codes",
            "Entry maintenance"
          ],
          "source": "w"
        }
      ],
      "glosses": [
        "Extremely thin; of utmost thinness"
      ],
      "id": "en-ultrathin-en-adj-LzU~Q9jQ",
      "links": [
        [
          "Extremely",
          "extremely"
        ],
        [
          "thin",
          "thin"
        ]
      ],
      "tags": [
        "not-comparable"
      ],
      "translations": [
        {
          "code": "el",
          "lang": "Greek",
          "roman": "ypérleptos",
          "sense": "extremely thin",
          "word": "υπέρλεπτος"
        }
      ]
    }
  ],
  "word": "ultrathin"
}

{
  "etymology_templates": [
    {
      "args": {
        "1": "en",
        "2": "ultra",
        "3": "thin"
      },
      "expansion": "ultra- + thin",
      "name": "prefix"
    }
  ],
  "etymology_text": "ultra- + thin",
  "head_templates": [
    {
      "args": {
        "1": "-"
      },
      "expansion": "ultrathin (not comparable)",
      "name": "en-adj"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "adj",
  "senses": [
    {
      "categories": [
        "English adjectives",
        "English entries with incorrect language header",
        "English lemmas",
        "English terms prefixed with ultra-",
        "English uncomparable adjectives",
        "Greek terms with redundant script codes"
      ],
      "glosses": [
        "Extremely thin; of utmost thinness"
      ],
      "links": [
        [
          "Extremely",
          "extremely"
        ],
        [
          "thin",
          "thin"
        ]
      ],
      "tags": [
        "not-comparable"
      ]
    }
  ],
  "translations": [
    {
      "code": "el",
      "lang": "Greek",
      "roman": "ypérleptos",
      "sense": "extremely thin",
      "word": "υπέρλεπτος"
    }
  ],
  "word": "ultrathin"
}