"◌̈" meaning in Portuguese

{
  "lang": "Portuguese",
  "lang_code": "pt",
  "pos": "character",
  "senses": [
    {
      "categories": [
        {
          "kind": "topical",
          "name": "Portuguese diacritical marks",
          "parents": [
            "Diacritical marks",
            "Letters, symbols, and punctuation",
            "Symbols",
            "Orthography",
            "Writing",
            "Human behaviour",
            "Language",
            "Human",
            "Communication",
            "All topics",
            "Fundamental"
          ],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Portuguese entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
          ],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Portuguese terms in nonstandard scripts",
          "parents": [
            "Terms in nonstandard scripts",
            "Entry maintenance"
          ],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Portuguese terms with redundant script codes",
          "parents": [
            "Terms with redundant script codes",
            "Entry maintenance"
          ],
          "source": "w"
        }
      ],
      "glosses": [
        "A diacritical mark of the Latin script, called trema (“trema”) in Portuguese, and found on Ü/ü."
      ],
      "id": "en-◌̈-pt-character-ZVttKOpr",
      "links": [
        [
          "diacritical mark",
          "diacritical mark"
        ],
        [
          "trema",
          "trema#Portuguese"
        ],
        [
          "Ü",
          "Ü#Portuguese"
        ],
        [
          "ü",
          "ü#Portuguese"
        ]
      ],
      "raw_glosses": [
        "(obsolete) A diacritical mark of the Latin script, called trema (“trema”) in Portuguese, and found on Ü/ü."
      ],
      "tags": [
        "diacritic",
        "obsolete"
      ]
    }
  ],
  "word": "◌̈"
}

{
  "lang": "Portuguese",
  "lang_code": "pt",
  "pos": "character",
  "senses": [
    {
      "categories": [
        "Portuguese diacritical marks",
        "Portuguese entries with incorrect language header",
        "Portuguese lemmas",
        "Portuguese terms in nonstandard scripts",
        "Portuguese terms with obsolete senses",
        "Portuguese terms with redundant script codes"
      ],
      "glosses": [
        "A diacritical mark of the Latin script, called trema (“trema”) in Portuguese, and found on Ü/ü."
      ],
      "links": [
        [
          "diacritical mark",
          "diacritical mark"
        ],
        [
          "trema",
          "trema#Portuguese"
        ],
        [
          "Ü",
          "Ü#Portuguese"
        ],
        [
          "ü",
          "ü#Portuguese"
        ]
      ],
      "raw_glosses": [
        "(obsolete) A diacritical mark of the Latin script, called trema (“trema”) in Portuguese, and found on Ü/ü."
      ],
      "tags": [
        "diacritic",
        "obsolete"
      ]
    }
  ],
  "word": "◌̈"
}