"perfidarum" meaning in Latin

{
  "categories": [
    {
      "kind": "other",
      "name": "Formes d’adjectifs en latin",
      "parents": [],
      "source": "w"
    },
    {
      "kind": "other",
      "name": "Latin",
      "orig": "latin",
      "parents": [],
      "source": "w"
    }
  ],
  "lang": "Latin",
  "lang_code": "la",
  "pos": "adj",
  "pos_title": "Forme d’adjectif",
  "senses": [
    {
      "form_of": [
        {
          "word": "perfidus"
        }
      ],
      "glosses": [
        "Génitif féminin pluriel de perfidus."
      ],
      "id": "fr-perfidarum-la-adj-JwLXbjfy"
    }
  ],
  "tags": [
    "form-of"
  ],
  "word": "perfidarum"
}

{
  "categories": [
    "Formes d’adjectifs en latin",
    "latin"
  ],
  "lang": "Latin",
  "lang_code": "la",
  "pos": "adj",
  "pos_title": "Forme d’adjectif",
  "senses": [
    {
      "form_of": [
        {
          "word": "perfidus"
        }
      ],
      "glosses": [
        "Génitif féminin pluriel de perfidus."
      ]
    }
  ],
  "tags": [
    "form-of"
  ],
  "word": "perfidarum"
}