"ст.-слав." meaning in Russian

{
  "forms": [
    {
      "form": "st.-slav.",
      "tags": [
        "romanization"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {
        "indecl": "1"
      },
      "expansion": "ст.-слав. • (st.-slav.) (indeclinable)",
      "name": "ru-adj"
    }
  ],
  "lang": "Russian",
  "lang_code": "ru",
  "pos": "adj",
  "senses": [
    {
      "alt_of": [
        {
          "extra": "(staroslavjánskij): OCS, Old Church Slavonic",
          "word": "старославя́нский"
        }
      ],
      "categories": [
        {
          "kind": "other",
          "name": "Russian entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
          ],
          "source": "w"
        },
        {
          "kind": "topical",
          "langcode": "ru",
          "name": "Linguistics",
          "orig": "ru:Linguistics",
          "parents": [
            "Language",
            "Social sciences",
            "Communication",
            "Sciences",
            "Society",
            "All topics",
            "Fundamental"
          ],
          "source": "w"
        }
      ],
      "glosses": [
        "abbreviation of старославя́нский (staroslavjánskij): OCS, Old Church Slavonic"
      ],
      "id": "en-ст.-слав.-ru-adj-dyWiIL8a",
      "links": [
        [
          "linguistics",
          "linguistics"
        ],
        [
          "старославя́нский",
          "старославянский#Russian"
        ],
        [
          "OCS",
          "OCS"
        ],
        [
          "Old Church Slavonic",
          "Old Church Slavonic"
        ]
      ],
      "raw_glosses": [
        "(linguistics) abbreviation of старославя́нский (staroslavjánskij): OCS, Old Church Slavonic"
      ],
      "tags": [
        "abbreviation",
        "alt-of",
        "indeclinable"
      ],
      "topics": [
        "human-sciences",
        "linguistics",
        "sciences"
      ]
    }
  ],
  "word": "ст.-слав."
}

{
  "forms": [
    {
      "form": "st.-slav.",
      "tags": [
        "romanization"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {
        "indecl": "1"
      },
      "expansion": "ст.-слав. • (st.-slav.) (indeclinable)",
      "name": "ru-adj"
    }
  ],
  "lang": "Russian",
  "lang_code": "ru",
  "pos": "adj",
  "senses": [
    {
      "alt_of": [
        {
          "extra": "(staroslavjánskij): OCS, Old Church Slavonic",
          "word": "старославя́нский"
        }
      ],
      "categories": [
        "Russian abbreviations",
        "Russian adjectives",
        "Russian entries with incorrect language header",
        "Russian indeclinable adjectives",
        "Russian lemmas",
        "Russian multiword terms",
        "Russian terms spelled with .",
        "Russian terms with redundant head parameter",
        "ru:Linguistics"
      ],
      "glosses": [
        "abbreviation of старославя́нский (staroslavjánskij): OCS, Old Church Slavonic"
      ],
      "links": [
        [
          "linguistics",
          "linguistics"
        ],
        [
          "старославя́нский",
          "старославянский#Russian"
        ],
        [
          "OCS",
          "OCS"
        ],
        [
          "Old Church Slavonic",
          "Old Church Slavonic"
        ]
      ],
      "raw_glosses": [
        "(linguistics) abbreviation of старославя́нский (staroslavjánskij): OCS, Old Church Slavonic"
      ],
      "tags": [
        "abbreviation",
        "alt-of",
        "indeclinable"
      ],
      "topics": [
        "human-sciences",
        "linguistics",
        "sciences"
      ]
    }
  ],
  "word": "ст.-слав."
}