"fff" meaning in Translingual

{
  "head_templates": [
    {
      "args": {
        "1": "mul",
        "2": "adverb"
      },
      "expansion": "fff",
      "name": "head"
    }
  ],
  "lang": "Translingual",
  "lang_code": "mul",
  "pos": "adv",
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "Musical symbols",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Pages with 1 entry",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Pages with entries",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Translingual entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
          ],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Translingual terms with 3 consecutive instances of the same letter",
          "parents": [],
          "source": "w"
        }
      ],
      "glosses": [
        "fortississimo, very very loud"
      ],
      "id": "en-fff-mul-adv-xH4K9zFS",
      "links": [
        [
          "fortississimo",
          "fortississimo"
        ]
      ],
      "related": [
        {
          "word": "ff"
        },
        {
          "word": "f"
        }
      ]
    }
  ],
  "word": "fff"
}

{
  "head_templates": [
    {
      "args": {
        "1": "mul",
        "2": "adverb"
      },
      "expansion": "fff",
      "name": "head"
    }
  ],
  "lang": "Translingual",
  "lang_code": "mul",
  "pos": "adv",
  "related": [
    {
      "word": "ff"
    },
    {
      "word": "f"
    }
  ],
  "senses": [
    {
      "categories": [
        "Musical symbols",
        "Pages with 1 entry",
        "Pages with entries",
        "Translingual adverbs",
        "Translingual entries with incorrect language header",
        "Translingual lemmas",
        "Translingual terms with 3 consecutive instances of the same letter"
      ],
      "glosses": [
        "fortississimo, very very loud"
      ],
      "links": [
        [
          "fortississimo",
          "fortississimo"
        ]
      ]
    }
  ],
  "word": "fff"
}