uncvsundoWhich spelling fits?

Quick tell: unc is a noun, undo is a verb, so they fill different roles in a sentence.

Which to use

“unc” is a noun and “undo” is a verb - they look or sound alike but fill different roles in a sentence.

#18,980
“unc” frequency rank
#13,631
“undo” frequency rank
32611
confusion score

Side-by-Side Comparison

Feature unc undo
Definition Clipping of uncle. To reverse the effects of an action.

Where the eye mixes unc and undo

Muted = shared; highlighted = the visual trap. They share 2 letters in sequence.

3 ch
unc
4 ch
undo

Visual trap between unc and undo

These two trip readers on the page rather than in the ear: unc is /ʌŋk/ while undo is /ʌnˈduː/. Spoken aloud the problem disappears. In writing it persists, because they differ by 1 letter(s) in length, and the parts of speech differ too (noun vs verb), which is usually the fastest check. Our composite confusion score for this pair is 32611, derived from the frequency rank of both members and their visual similarity.

unc is recorded at frequency rank #18,980, classified as anoun, pronounced /ʌŋk/. undo is at rank #13,631, tagged as averb, pronounced /ʌnˈduː/.

Glosses for this pair are partially populated in our dataset, but the full side-by-side definitions above should still guide you to the right choice.

With a confusion score of 32611, this pair ranks #336,364 of 530,003 scored English confusable pairs - roughly mid-pack for confusability.

Orthographic DNA of unc vs undo

Shared letters: nu. Private to "unc": c. Private to "undo": do.

"unc" · 3 letters · shape VCC  ·  "undo" · 4 letters · shape VCCV

Known mistypes of this pair

  • undonudo · udno · unddo · unndo · unod

Frequently Asked Questions

Do "unc" and "undo" mean the same thing in a sentence?
No - they are not even the same part of speech. "unc" is a noun and "undo" a verb, so a sentence built for one is usually ungrammatical with the other.
In ordinary English text, does "unc" or "undo" show up more?
"undo" is the more common of the two: it sits at frequency rank #13,631 in our English list, against #18,980 for "unc". The two are close in frequency, so neither is a safe default; check the meaning rather than guessing.

After this comparison

Pronunciation already separates them, if the page still looks alike, the dictionary links below settle it.

  • Full dictionary entry for "unc" with definition, IPA, and generated misspellings. Word entry
  • Full dictionary entry for "undo" - compare definitions side by side with the headword page. Word entry
  • This pair ranks #336,364 of 530,003 scored English confusable pairs in this corpus vintage. Corpus statistics
  • "unc" and "undo" also get mixed up with nearby pairs, the highest-scored neighbour is "UAS vs unc". Nearby pair
  • Recorded mistypes exist for at least one side of this pair, useful when a spell-checker or OCR lands on the wrong form. See mistypes

Confusion rank #336,364 of 530,003 scored English pairs, corpus vintage 2026-09-03, not spelling advice.

Source: Wiktionary (via kaikki.org) Structured Wiktionary extract

Source: FrequencyWords open word-frequency list