Which to use
“underline” is a noun and “underlying” is an adjective - they look or sound alike but fill different roles in a sentence.
- #29,874
- “underline” frequency rank
- #5,464
- “underlying” frequency rank
- 35338
- confusion score
Side-by-Side Comparison
| Feature | underline | underlying |
|---|---|---|
| Definition | A line placed underneath a piece of text in order to provide emphasis or to indicate that it should be viewed in italics or (in electronic documents) that it acts as a hyperlink. | lying underneath |
Letter map: underline vs underlying
Shared letters muted; letters that set underline and underlying apart highlighted. Shared run: 8.
Part-of-speech tell for underline / underlying
Our dataset has no pronunciation recorded for both members, so the reliable separator here is grammatical: underline is anoun and underlyinganadjective. On the page they differ by 1 letter(s) in length. Our composite confusion score for this pair is 35338, derived from the frequency rank of both members and their visual similarity.
underline is recorded at frequency rank #29,874, classified as anoun, pronounced /ˈʌndɚˌlaɪn/. underlying is at rank #5,464, tagged as anadj.
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 35338, this pair ranks #312,820 of 530,003 scored English confusable pairs - roughly mid-pack for confusability.
Orthographic DNA of underline vs underlying
Shared letters: deilnru. Private to "underline": -. Private to "underlying": gy.
"underline" · 9 letters · shape VCCVCCVCV · "underlying" · 10 letters · shape VCCVCCVVCC
Known mistypes of this pair
- underline ← nuderline · udnerline · undderline · undelrine · underilne · underlien · underlinne · underlline
- underlying ← nuderlying · udnerlying · undderlying · undelrying · underliyng · underllying · underlyign · underlyingg
Frequently Asked Questions
Is swapping "underline" for "underlying" ever safe?
In ordinary English text, does "underline" or "underlying" show up more?
What to do next
Done with this confusable. These links stay specific to "underline" and "underlying".
- Full dictionary entry for "underline" with definition, IPA, and generated misspellings. Word entry
- Full dictionary entry for "underlying" - compare definitions side by side with the headword page. Word entry
- This pair ranks #312,820 of 530,003 scored English confusable pairs in this corpus vintage. Corpus statistics
- "underline" and "underlying" also get mixed up with nearby pairs, the highest-scored neighbour is "underline vs undertone". 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 #312,820 of 530,003 scored English pairs, corpus vintage 2026-09-03, not spelling advice.