"-iest" meaning in Anglais

{
  "categories": [
    {
      "kind": "other",
      "name": "Formes de suffixes en anglais",
      "parents": [],
      "source": "w"
    },
    {
      "kind": "other",
      "name": "Anglais",
      "orig": "anglais",
      "parents": [],
      "source": "w"
    }
  ],
  "lang": "Anglais",
  "lang_code": "en",
  "pos": "suffix",
  "pos_title": "Forme de suffixe 3",
  "senses": [
    {
      "form_of": [
        {
          "word": "-y"
        }
      ],
      "glosses": [
        "Superlatif de -y."
      ],
      "id": "fr--iest-en-suffix-4aKkI5fG"
    }
  ],
  "tags": [
    "form-of",
    "morpheme"
  ],
  "word": "-iest"
}

{
  "categories": [
    "Formes de suffixes en anglais",
    "anglais"
  ],
  "lang": "Anglais",
  "lang_code": "en",
  "pos": "suffix",
  "pos_title": "Forme de suffixe 3",
  "senses": [
    {
      "form_of": [
        {
          "word": "-y"
        }
      ],
      "glosses": [
        "Superlatif de -y."
      ]
    }
  ],
  "tags": [
    "form-of",
    "morpheme"
  ],
  "word": "-iest"
}