"юность" meaning in Vieux slave

{
  "categories": [
    {
      "kind": "other",
      "name": "Dérivations en vieux slave",
      "parents": [],
      "source": "w"
    },
    {
      "kind": "other",
      "name": "Mots en vieux slave suffixés avec -ость",
      "parents": [],
      "source": "w"
    },
    {
      "kind": "other",
      "name": "Noms communs en vieux slave",
      "parents": [],
      "source": "w"
    },
    {
      "kind": "other",
      "name": "Vieux slave",
      "orig": "vieux slave",
      "parents": [],
      "source": "w"
    }
  ],
  "etymology_texts": [
    "Dérivé de юнъ, junŭ (« jeune »), avec le suffixe -ость, -ostĭ."
  ],
  "lang": "Vieux slave",
  "lang_code": "cu",
  "pos": "noun",
  "pos_title": "Nom commun",
  "raw_tags": [
    "junostĭ"
  ],
  "senses": [
    {
      "glosses": [
        "Jeunesse, adolescence."
      ],
      "id": "fr-юность-cu-noun-WmSeBrIV"
    }
  ],
  "tags": [
    "feminine"
  ],
  "word": "юность"
}

{
  "categories": [
    "Dérivations en vieux slave",
    "Mots en vieux slave suffixés avec -ость",
    "Noms communs en vieux slave",
    "vieux slave"
  ],
  "etymology_texts": [
    "Dérivé de юнъ, junŭ (« jeune »), avec le suffixe -ость, -ostĭ."
  ],
  "lang": "Vieux slave",
  "lang_code": "cu",
  "pos": "noun",
  "pos_title": "Nom commun",
  "raw_tags": [
    "junostĭ"
  ],
  "senses": [
    {
      "glosses": [
        "Jeunesse, adolescence."
      ]
    }
  ],
  "tags": [
    "feminine"
  ],
  "word": "юность"
}