"быкъ" meaning in Vieux slave

{
  "categories": [
    {
      "kind": "other",
      "name": "Mots en vieux slave issus d’une onomatopée",
      "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"
    }
  ],
  "derived": [
    {
      "lang": "Bulgare",
      "lang_code": "bg",
      "word": "бик"
    },
    {
      "lang": "Polonais",
      "lang_code": "pl",
      "word": "byk"
    },
    {
      "lang": "Russe",
      "lang_code": "ru",
      "word": "бык"
    },
    {
      "lang": "Slovène",
      "lang_code": "sl",
      "word": "bik"
    },
    {
      "lang": "Tchèque",
      "lang_code": "cs",
      "word": "býk"
    }
  ],
  "etymology_texts": [
    "D’une onomatopée beuh, bouh qui donne le russe бычить, le tchèque bučet (« beugler »), bukač."
  ],
  "lang": "Vieux slave",
  "lang_code": "cu",
  "pos": "noun",
  "pos_title": "Nom commun",
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "Mammifères en vieux slave",
          "parents": [],
          "source": "w"
        }
      ],
      "glosses": [
        "Taureau."
      ],
      "id": "fr-быкъ-cu-noun-vpArBmkQ",
      "topics": [
        "mammalogy"
      ]
    }
  ],
  "tags": [
    "masculine"
  ],
  "word": "быкъ"
}

{
  "categories": [
    "Mots en vieux slave issus d’une onomatopée",
    "Noms communs en vieux slave",
    "vieux slave"
  ],
  "derived": [
    {
      "lang": "Bulgare",
      "lang_code": "bg",
      "word": "бик"
    },
    {
      "lang": "Polonais",
      "lang_code": "pl",
      "word": "byk"
    },
    {
      "lang": "Russe",
      "lang_code": "ru",
      "word": "бык"
    },
    {
      "lang": "Slovène",
      "lang_code": "sl",
      "word": "bik"
    },
    {
      "lang": "Tchèque",
      "lang_code": "cs",
      "word": "býk"
    }
  ],
  "etymology_texts": [
    "D’une onomatopée beuh, bouh qui donne le russe бычить, le tchèque bučet (« beugler »), bukač."
  ],
  "lang": "Vieux slave",
  "lang_code": "cu",
  "pos": "noun",
  "pos_title": "Nom commun",
  "senses": [
    {
      "categories": [
        "Mammifères en vieux slave"
      ],
      "glosses": [
        "Taureau."
      ],
      "topics": [
        "mammalogy"
      ]
    }
  ],
  "tags": [
    "masculine"
  ],
  "word": "быкъ"
}