"underletter" meaning in English

{
  "etymology_templates": [
    {
      "args": {
        "1": "en",
        "2": "underlet",
        "3": "er"
      },
      "expansion": "underlet + -er",
      "name": "suffix"
    }
  ],
  "etymology_text": "From underlet + -er.",
  "forms": [
    {
      "form": "underletters",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "underletter (plural underletters)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "English entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
          ],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "English terms suffixed with -er",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Pages with 1 entry",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Pages with entries",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "topical",
          "langcode": "en",
          "name": "Property law",
          "orig": "en:Property law",
          "parents": [
            "Law",
            "Justice",
            "Society",
            "All topics",
            "Fundamental"
          ],
          "source": "w"
        }
      ],
      "glosses": [
        "Synonym of sublessor."
      ],
      "id": "en-underletter-en-noun-ihnYGVY5",
      "links": [
        [
          "property law",
          "property law"
        ],
        [
          "sublessor",
          "sublessor#English"
        ]
      ],
      "raw_glosses": [
        "(property law) Synonym of sublessor."
      ],
      "synonyms": [
        {
          "word": "sublessor"
        },
        {
          "word": "underlessor"
        },
        {
          "word": "sublandlord"
        },
        {
          "word": "underlandlord"
        },
        {
          "word": "subletter"
        },
        {
          "tags": [
            "informal"
          ],
          "word": "subleaser"
        },
        {
          "word": "underleaser"
        },
        {
          "english": "as tenant",
          "word": "head tenant"
        },
        {
          "word": "superior tenant"
        },
        {
          "tags": [
            "synonym",
            "synonym-of"
          ],
          "word": "sublessor"
        }
      ],
      "topics": [
        "law",
        "property"
      ]
    }
  ],
  "word": "underletter"
}

{
  "etymology_templates": [
    {
      "args": {
        "1": "en",
        "2": "underlet",
        "3": "er"
      },
      "expansion": "underlet + -er",
      "name": "suffix"
    }
  ],
  "etymology_text": "From underlet + -er.",
  "forms": [
    {
      "form": "underletters",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "underletter (plural underletters)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        "English countable nouns",
        "English entries with incorrect language header",
        "English lemmas",
        "English nouns",
        "English terms suffixed with -er",
        "Pages with 1 entry",
        "Pages with entries",
        "en:Property law"
      ],
      "glosses": [
        "Synonym of sublessor."
      ],
      "links": [
        [
          "property law",
          "property law"
        ],
        [
          "sublessor",
          "sublessor#English"
        ]
      ],
      "raw_glosses": [
        "(property law) Synonym of sublessor."
      ],
      "synonyms": [
        {
          "word": "sublessor"
        },
        {
          "word": "underlessor"
        },
        {
          "word": "sublandlord"
        },
        {
          "word": "underlandlord"
        },
        {
          "word": "subletter"
        },
        {
          "tags": [
            "informal"
          ],
          "word": "subleaser"
        },
        {
          "word": "underleaser"
        },
        {
          "english": "as tenant",
          "word": "head tenant"
        },
        {
          "word": "superior tenant"
        },
        {
          "tags": [
            "synonym",
            "synonym-of"
          ],
          "word": "sublessor"
        }
      ],
      "topics": [
        "law",
        "property"
      ]
    }
  ],
  "word": "underletter"
}