"efficacissime" meaning in Latin

{
  "forms": [
    {
      "form": "efficācissimē",
      "tags": [
        "canonical"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {
        "1": "la",
        "2": "adverb forms",
        "cat2": "superlative adverbs",
        "head": "efficācissimē"
      },
      "expansion": "efficācissimē",
      "name": "head"
    }
  ],
  "lang": "Latin",
  "lang_code": "la",
  "pos": "adv",
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "Latin entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
          ],
          "source": "w"
        }
      ],
      "form_of": [
        {
          "word": "efficāciter"
        }
      ],
      "glosses": [
        "superlative degree of efficāciter"
      ],
      "id": "en-efficacissime-la-adv-GR7oa0Kc",
      "links": [
        [
          "efficāciter",
          "efficaciter#Latin"
        ]
      ],
      "tags": [
        "form-of",
        "superlative"
      ]
    }
  ],
  "word": "efficacissime"
}

{
  "forms": [
    {
      "form": "efficācissimē",
      "tags": [
        "canonical"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {
        "1": "la",
        "2": "adverb forms",
        "cat2": "superlative adverbs",
        "head": "efficācissimē"
      },
      "expansion": "efficācissimē",
      "name": "head"
    }
  ],
  "lang": "Latin",
  "lang_code": "la",
  "pos": "adv",
  "senses": [
    {
      "categories": [
        "Latin adverb forms",
        "Latin entries with incorrect language header",
        "Latin non-lemma forms",
        "Latin superlative adverbs"
      ],
      "form_of": [
        {
          "word": "efficāciter"
        }
      ],
      "glosses": [
        "superlative degree of efficāciter"
      ],
      "links": [
        [
          "efficāciter",
          "efficaciter#Latin"
        ]
      ],
      "tags": [
        "form-of",
        "superlative"
      ]
    }
  ],
  "word": "efficacissime"
}