"-thumb" meaning in German

{
  "head_templates": [
    {
      "args": {
        "1": "de",
        "2": "suffix",
        "g": "n",
        "g2": "m"
      },
      "expansion": "-thumb n or m",
      "name": "head"
    }
  ],
  "lang": "German",
  "lang_code": "de",
  "pos": "suffix",
  "senses": [
    {
      "alt_of": [
        {
          "word": "-tum"
        }
      ],
      "categories": [
        {
          "kind": "other",
          "name": "German entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
          ],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "German suffixes with multiple genders",
          "parents": [
            "Suffixes with multiple genders",
            "Suffixes by gender",
            "Suffixes",
            "Morphemes",
            "Lemmas"
          ],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Pages with 1 entry",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Pages with entries",
          "parents": [],
          "source": "w"
        }
      ],
      "glosses": [
        "Obsolete spelling of -tum."
      ],
      "id": "en--thumb-de-suffix-EiooeSkH",
      "links": [
        [
          "-tum",
          "-tum#German"
        ]
      ],
      "tags": [
        "alt-of",
        "masculine",
        "morpheme",
        "neuter",
        "obsolete"
      ]
    }
  ],
  "word": "-thumb"
}

{
  "head_templates": [
    {
      "args": {
        "1": "de",
        "2": "suffix",
        "g": "n",
        "g2": "m"
      },
      "expansion": "-thumb n or m",
      "name": "head"
    }
  ],
  "lang": "German",
  "lang_code": "de",
  "pos": "suffix",
  "senses": [
    {
      "alt_of": [
        {
          "word": "-tum"
        }
      ],
      "categories": [
        "German entries with incorrect language header",
        "German lemmas",
        "German masculine suffixes",
        "German neuter suffixes",
        "German obsolete forms",
        "German suffixes",
        "German suffixes with multiple genders",
        "Pages with 1 entry",
        "Pages with entries"
      ],
      "glosses": [
        "Obsolete spelling of -tum."
      ],
      "links": [
        [
          "-tum",
          "-tum#German"
        ]
      ],
      "tags": [
        "alt-of",
        "masculine",
        "morpheme",
        "neuter",
        "obsolete"
      ]
    }
  ],
  "word": "-thumb"
}