"посеревши" meaning in Russian

{
  "forms": [
    {
      "form": "посере́вши",
      "tags": [
        "canonical"
      ]
    },
    {
      "form": "poserévši",
      "tags": [
        "romanization"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {
        "1": "ru",
        "2": "past adverbial participle",
        "head": "посере́вши"
      },
      "expansion": "посере́вши • (poserévši)",
      "name": "head"
    }
  ],
  "lang": "Russian",
  "lang_code": "ru",
  "pos": "verb",
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "Pages with 1 entry",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Pages with entries",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Russian entries with incorrect language header",
          "parents": [],
          "source": "w"
        }
      ],
      "form_of": [
        {
          "extra": "poserétʹ",
          "word": "посере́ть"
        }
      ],
      "glosses": [
        "past adverbial perfective participle of посере́ть (poserétʹ)"
      ],
      "id": "en-посеревши-ru-verb-b4f-gV4Z",
      "links": [
        [
          "посере́ть",
          "посереть#Russian"
        ]
      ],
      "tags": [
        "adverbial",
        "form-of",
        "participle",
        "past",
        "perfective"
      ]
    }
  ],
  "sounds": [
    {
      "ipa": "[pəsʲɪˈrʲefʂɨ]"
    }
  ],
  "word": "посеревши"
}

{
  "forms": [
    {
      "form": "посере́вши",
      "tags": [
        "canonical"
      ]
    },
    {
      "form": "poserévši",
      "tags": [
        "romanization"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {
        "1": "ru",
        "2": "past adverbial participle",
        "head": "посере́вши"
      },
      "expansion": "посере́вши • (poserévši)",
      "name": "head"
    }
  ],
  "lang": "Russian",
  "lang_code": "ru",
  "pos": "verb",
  "senses": [
    {
      "categories": [
        "Pages with 1 entry",
        "Pages with entries",
        "Russian 4-syllable words",
        "Russian entries with incorrect language header",
        "Russian non-lemma forms",
        "Russian past adverbial participles",
        "Russian terms with IPA pronunciation"
      ],
      "form_of": [
        {
          "extra": "poserétʹ",
          "word": "посере́ть"
        }
      ],
      "glosses": [
        "past adverbial perfective participle of посере́ть (poserétʹ)"
      ],
      "links": [
        [
          "посере́ть",
          "посереть#Russian"
        ]
      ],
      "tags": [
        "adverbial",
        "form-of",
        "participle",
        "past",
        "perfective"
      ]
    }
  ],
  "sounds": [
    {
      "ipa": "[pəsʲɪˈrʲefʂɨ]"
    }
  ],
  "word": "посеревши"
}