"sís" meaning in Icelandic

{
  "etymology_templates": [
    {
      "args": {
        "1": "is",
        "2": "en",
        "3": "cheese"
      },
      "expansion": "English cheese",
      "name": "der"
    }
  ],
  "etymology_text": "From English cheese.",
  "head_templates": [
    {
      "args": {
        "1": "is",
        "2": "interjection"
      },
      "expansion": "sís",
      "name": "head"
    }
  ],
  "lang": "Icelandic",
  "lang_code": "is",
  "pos": "intj",
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "Icelandic entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
          ],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Pages with 2 entries",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Pages with entries",
          "parents": [],
          "source": "w"
        }
      ],
      "glosses": [
        "cheese (sound used to produce a smile on photographs)"
      ],
      "id": "en-sís-is-intj-yNhvcNAD",
      "links": [
        [
          "cheese",
          "cheese"
        ]
      ]
    }
  ],
  "sounds": [
    {
      "ipa": "/siːs/"
    },
    {
      "rhymes": "-iːs"
    },
    {
      "homophone": "stripped-by-parse_pron_post_template_fn"
    }
  ],
  "word": "sís"
}

{
  "etymology_templates": [
    {
      "args": {
        "1": "is",
        "2": "en",
        "3": "cheese"
      },
      "expansion": "English cheese",
      "name": "der"
    }
  ],
  "etymology_text": "From English cheese.",
  "head_templates": [
    {
      "args": {
        "1": "is",
        "2": "interjection"
      },
      "expansion": "sís",
      "name": "head"
    }
  ],
  "lang": "Icelandic",
  "lang_code": "is",
  "pos": "intj",
  "senses": [
    {
      "categories": [
        "Icelandic entries with incorrect language header",
        "Icelandic interjections",
        "Icelandic lemmas",
        "Icelandic palindromes",
        "Icelandic terms derived from English",
        "Pages with 2 entries",
        "Pages with entries",
        "Rhymes:Icelandic/iːs",
        "Rhymes:Icelandic/iːs/1 syllable"
      ],
      "glosses": [
        "cheese (sound used to produce a smile on photographs)"
      ],
      "links": [
        [
          "cheese",
          "cheese"
        ]
      ]
    }
  ],
  "sounds": [
    {
      "ipa": "/siːs/"
    },
    {
      "rhymes": "-iːs"
    },
    {
      "homophone": "stripped-by-parse_pron_post_template_fn"
    }
  ],
  "word": "sís"
}