English word origin

Etymology of undo

From Middle English undōn, from Old English ondōn, from Proto-West Germanic *andadōn (“to undo”), equivalent to un- + do. Cognate with West Frisian ûndwaan, ûntdwaan (“to undo; rid”), Dutch ontdoen (“to undo”).

2 source sectionsExtended source reportWiktionary original ↗

In this entry · 2 source sections

The source etymologies

Wiktionary via Kaikki / Wiktextract

The source reports below are imported and unreviewed by *SET-U. Separate numbered origins and differing source variants are preserved; agreement within this extraction is not independent corroboration.

Source etymology 1 · variant 1/2

Original entry ↗

noun

An operation that reverses a previous action.

Selected source glosses provide context, not a complete modern definition inventory

Relationships mentioned by the source

These are extracted mentions, not a timeline or a verified sequence of immediate parents.

Inherited-form mentionundōnenm
Inherited-form mentionondōnang
Inherited-form mention*andadōngmw-pro · to undo
Cognate mentionûndwaanfy
Cognate mentionontdoennl · to undo

Inspect preserved source fields

Raw extraction fields are retained for auditing. Their order does not establish ancestry.

{
  "templates": [
    {
      "name": "ety",
      "args": {
        "1": "en",
        "2": ":inh",
        "3": "enm:undōn"
      },
      "expansion": "[Appendix:Glossary#inherited|Inherited]] from\", \"keyword\" : \"inherited\" } ], \"lang_name\" : \"English\", \"term\" : \"undo\", \"status\" : \"ok\", \"lang\" : \"en\" }\" data-lang=\"en\" data-title=\"undo\">"
    },
    {
      "name": "inh",
      "args": {
        "1": "en",
        "2": "enm",
        "3": "undōn"
      },
      "expansion": "Middle English undōn"
    },
    {
      "name": "inh",
      "args": {
        "1": "en",
        "2": "ang",
        "3": "ondōn"
      },
      "expansion": "Old English ondōn"
    },
    {
      "name": "inh",
      "args": {
        "1": "en",
        "2": "gmw-pro",
        "3": "*andadōn",
        "t": "to undo"
      },
      "expansion": "Proto-West Germanic *andadōn (“to undo”)"
    },
    {
      "name": "pre",
      "args": {
        "1": "en",
        "2": "un",
        "3": "do",
        "id1": "reversive"
      },
      "expansion": "un- + do"
    },
    {
      "name": "cog",
      "args": {
        "1": "fy",
        "2": "ûndwaan"
      },
      "expansion": "West Frisian ûndwaan"
    },
    {
      "name": "cog",
      "args": {
        "1": "nl",
        "2": "ontdoen",
        "t": "to undo"
      },
      "expansion": "Dutch ontdoen (“to undo”)"
    },
    {
      "name": "ety",
      "args": {
        "1": "en",
        "2": ":inh",
        "3": "enm:undōn"
      },
      "expansion": ""
    }
  ],
  "links": [
    [
      "undōn",
      "undon#Middle_English"
    ],
    [
      "ondōn",
      "ondon#Old_English"
    ],
    [
      "*andadōn",
      "Reconstruction:Proto-West Germanic/andadōn"
    ],
    [
      "un-",
      "un-#English:_reversive"
    ],
    [
      "do",
      "do#English"
    ],
    [
      "ûndwaan",
      "ûndwaan#West_Frisian"
    ],
    [
      "ûntdwaan",
      "ûntdwaan#West_Frisian"
    ],
    [
      "ontdoen",
      "ontdoen#Dutch"
    ]
  ],
  "references": [],
  "descendants": [],
  "lexical": [
    {
      "pos": "noun",
      "glosses": [
        "An operation that reverses a previous action."
      ],
      "tags": [
        "transitive"
      ],
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Source etymology 1 · variant 2/2

Original entry ↗

verb

To reverse the effects of an action. · To unfasten. · To unfasten the clothing of (a person). · To impoverish or ruin, as in reputation; to cause the downfall of.

Selected source glosses provide context, not a complete modern definition inventory

Relationships mentioned by the source

These are extracted mentions, not a timeline or a verified sequence of immediate parents.

Inherited-form mentionundōnenm
Inherited-form mentionondōnang
Inherited-form mention*andadōngmw-pro · to undo
Cognate mentionûndwaanfy
Cognate mentionontdoennl · to undo

Inspect preserved source fields

Raw extraction fields are retained for auditing. Their order does not establish ancestry.

{
  "templates": [
    {
      "name": "ety",
      "args": {
        "1": "en",
        "2": ":inh",
        "3": "enm:undōn"
      },
      "expansion": "[Appendix:Glossary#inherited|Inherited]] from\", \"keyword\" : \"inherited\" } ], \"lang_name\" : \"English\", \"term\" : \"undo\", \"status\" : \"ok\", \"lang\" : \"en\" }\" data-lang=\"en\" data-title=\"undo\">"
    },
    {
      "name": "inh",
      "args": {
        "1": "en",
        "2": "enm",
        "3": "undōn"
      },
      "expansion": "Middle English undōn"
    },
    {
      "name": "inh",
      "args": {
        "1": "en",
        "2": "ang",
        "3": "ondōn"
      },
      "expansion": "Old English ondōn"
    },
    {
      "name": "inh",
      "args": {
        "1": "en",
        "2": "gmw-pro",
        "3": "*andadōn",
        "t": "to undo"
      },
      "expansion": "Proto-West Germanic *andadōn (“to undo”)"
    },
    {
      "name": "pre",
      "args": {
        "1": "en",
        "2": "un",
        "3": "do",
        "id1": "reversive"
      },
      "expansion": "un- + do"
    },
    {
      "name": "cog",
      "args": {
        "1": "fy",
        "2": "ûndwaan"
      },
      "expansion": "West Frisian ûndwaan"
    },
    {
      "name": "cog",
      "args": {
        "1": "nl",
        "2": "ontdoen",
        "t": "to undo"
      },
      "expansion": "Dutch ontdoen (“to undo”)"
    },
    {
      "name": "ety",
      "args": {
        "1": "en",
        "2": ":inh",
        "3": "enm:undōn"
      },
      "expansion": ""
    }
  ],
  "links": [
    [
      "undōn",
      "undon#Middle_English"
    ],
    [
      "ondōn",
      "ondon#Old_English"
    ],
    [
      "*andadōn",
      "Reconstruction:Proto-West Germanic/andadōn"
    ],
    [
      "un-",
      "un-#English:_reversive"
    ],
    [
      "do",
      "do#English"
    ],
    [
      "ûndwaan",
      "ûndwaan#West_Frisian"
    ],
    [
      "ûntdwaan",
      "ûntdwaan#West_Frisian"
    ],
    [
      "ontdoen",
      "ontdoen#Dutch"
    ]
  ],
  "references": [],
  "descendants": [
    {
      "lang": "Welsh",
      "lang_code": "cy",
      "word": "andwyo",
      "raw_tags": [
        "borrowed"
      ]
    }
  ],
  "lexical": [
    {
      "pos": "verb",
      "glosses": [
        "To reverse the effects of an action.",
        "To unfasten.",
        "To unfasten the clothing of (a person).",
        "To impoverish or ruin, as in reputation; to cause the downfall of."
      ],
      "tags": [
        "transitive",
        "colloquial",
        "figuratively"
      ],
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}

Where this record stops

This page does not supply an independently verified sound-change sequence, first-use manuscript or complete family tree unless a cited analysis explicitly establishes one. Missing detail here is a limit of this record—not a claim that humanity knows nothing more.

An older meaning does not determine what a word must mean today. Follow the sources, preserve disagreements, and keep ancestry separate from interpretation.

Contribute located evidence for undo →

Source and snapshot

Imported from Wiktionary contributors; extracted by Tatu Ylonen / Wiktextract / Kaikki.org. Selected fields are reformatted and grouped; wording, source identity and etymology sections are retained. CC-BY-SA-4.0 applies to the imported source material.

Dump: 2026-10-01 · Extracted: 2026-10-30. These are snapshot dates, not the word’s first attestation or the page’s revision date.

Source entry and bibliography ↗Wiktionary revision history ↗Acquisition and rights ledger

Machine-source provenance

Source SHA-256: 5ff2c072f8099f2d2ce484bd6957bf179f046d2ad37bc36555edf8bb84cb5291
Import run: 73216b9a9b78ed3830994bf853103716f5a4dc57099e371e9f8fdc468facca26
Permanent entry ID: w-dW5kbw