"-ef" meaning in Volapük

{
  "head_templates": [
    {
      "args": {
        "1": "vo",
        "2": "suffix"
      },
      "expansion": "-ef",
      "name": "head"
    }
  ],
  "lang": "Volapük",
  "lang_code": "vo",
  "pos": "suffix",
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "Pages with 2 entries",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Pages with entries",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Volapük entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
          ],
          "source": "w"
        }
      ],
      "glosses": [
        "Used to indicate a group of people"
      ],
      "id": "en--ef-vo-suffix-2uroZYzD",
      "tags": [
        "morpheme"
      ]
    }
  ],
  "word": "-ef"
}

{
  "head_templates": [
    {
      "args": {
        "1": "vo",
        "2": "suffix"
      },
      "expansion": "-ef",
      "name": "head"
    }
  ],
  "lang": "Volapük",
  "lang_code": "vo",
  "pos": "suffix",
  "senses": [
    {
      "categories": [
        "Pages with 2 entries",
        "Pages with entries",
        "Volapük entries with incorrect language header",
        "Volapük lemmas",
        "Volapük suffixes"
      ],
      "glosses": [
        "Used to indicate a group of people"
      ],
      "tags": [
        "morpheme"
      ]
    }
  ],
  "word": "-ef"
}