"-ksi-" meaning in Finnish

{
  "etymology_templates": [
    {
      "args": {
        "1": "fi",
        "2": "-s",
        "id": "nominal"
      },
      "expansion": "-s",
      "name": "m"
    },
    {
      "args": {
        "1": "fi",
        "2": "-os"
      },
      "expansion": "-os",
      "name": "m"
    },
    {
      "args": {
        "1": "fi",
        "2": "-us",
        "id": "action or event"
      },
      "expansion": "-us",
      "name": "m"
    }
  ],
  "etymology_text": "Originally from the plural stem of -s (in some cases also -os, -us; all deverbal noun suffixes), by analogy with plural derivatives of deverbal nouns using that suffix.",
  "head_templates": [
    {
      "args": {
        "1": "fi",
        "2": "interfix"
      },
      "expansion": "-ksi-",
      "name": "head"
    }
  ],
  "lang": "Finnish",
  "lang_code": "fi",
  "pos": "interfix",
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "Finnish entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
          ],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Finnish interfixes",
          "parents": [],
          "source": "w"
        }
      ],
      "glosses": [
        "Used in adverbs between a verb and a locative case (especially an internal locative case, like inessive, illative or elative) ending."
      ],
      "id": "en--ksi--fi-interfix-rVORPSeH",
      "synonyms": [
        {
          "word": "-uksi-"
        }
      ],
      "tags": [
        "morpheme"
      ]
    }
  ],
  "word": "-ksi-"
}

{
  "etymology_templates": [
    {
      "args": {
        "1": "fi",
        "2": "-s",
        "id": "nominal"
      },
      "expansion": "-s",
      "name": "m"
    },
    {
      "args": {
        "1": "fi",
        "2": "-os"
      },
      "expansion": "-os",
      "name": "m"
    },
    {
      "args": {
        "1": "fi",
        "2": "-us",
        "id": "action or event"
      },
      "expansion": "-us",
      "name": "m"
    }
  ],
  "etymology_text": "Originally from the plural stem of -s (in some cases also -os, -us; all deverbal noun suffixes), by analogy with plural derivatives of deverbal nouns using that suffix.",
  "head_templates": [
    {
      "args": {
        "1": "fi",
        "2": "interfix"
      },
      "expansion": "-ksi-",
      "name": "head"
    }
  ],
  "lang": "Finnish",
  "lang_code": "fi",
  "pos": "interfix",
  "senses": [
    {
      "categories": [
        "Finnish entries with incorrect language header",
        "Finnish interfixes",
        "Finnish lemmas"
      ],
      "glosses": [
        "Used in adverbs between a verb and a locative case (especially an internal locative case, like inessive, illative or elative) ending."
      ],
      "tags": [
        "morpheme"
      ]
    }
  ],
  "synonyms": [
    {
      "word": "-uksi-"
    }
  ],
  "word": "-ksi-"
}