Which to use
“ulcer” is a noun and “under” is a preposition - they look or sound alike but fill different roles in a sentence.
- #28,066
- “ulcer” frequency rank
- #180
- “under” frequency rank
- 28246
- confusion score
Side-by-Side Comparison
| Feature | ulcer | under |
|---|---|---|
| Definition | An open sore of the skin, eyes or mucous membrane, often caused by an initial abrasion and generally maintained by an inflammation and/or an infection. | Beneath; below; at or to the bottom of, or the area covered or surmounted by. |
Where the eye mixes ulcer and under
Muted = shared; highlighted = the visual trap. They share 3 letters in sequence.
Visual trap between ulcer and under
These two trip readers on the page rather than in the ear: ulcer is /ˈʌlsə/ while under is /ˈʌndə/. Spoken aloud the problem disappears. In writing it persists, because they share most of their letters but differ in 2 positions, and the parts of speech differ too (noun vs preposition), which is usually the fastest check. Our composite confusion score for this pair is 28246, derived from the frequency rank of both members and their visual similarity.
ulcer is recorded at frequency rank #28,066, classified as anoun, pronounced /ˈʌlsə/. under is at rank #180, tagged as aprep, pronounced /ˈʌndə/.
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 28246, this pair ranks #372,559 of 530,003 scored English confusable pairs - roughly mid-pack for confusability.
Orthographic DNA of ulcer vs under
Shared letters: eru. Private to "ulcer": cl. Private to "under": dn.
"ulcer" · 5 letters · shape VCCVC · "under" · 5 letters · shape VCCVC
Known mistypes of this pair
Frequently Asked Questions
Is swapping "ulcer" for "under" ever safe?
Which is more common, "ulcer" or "under"?
Useful next steps
Eye-level mix-up between "ulcer" and "under" is sorted above. Next: full entries or other pairs that share a letter shape.
- Full dictionary entry for "ulcer" with definition, IPA, and generated misspellings. Word entry
- Full dictionary entry for "under" - compare definitions side by side with the headword page. Word entry
- This pair ranks #372,559 of 530,003 scored English confusable pairs in this corpus vintage. Corpus statistics
- "ulcer" and "under" also get mixed up with nearby pairs, the highest-scored neighbour is "under vs unsee". 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 #372,559 of 530,003 scored English pairs, corpus vintage 2026-09-03, not spelling advice.