underlinevsunderlinedWhich spelling fits?

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

Which to use

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

#29,874
“underline” frequency rank
#25,629
“underlined” frequency rank
55503
confusion score

Side-by-Side Comparison

Feature underline underlined
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. simple past and past participle of underline

Letter map: underline vs underlined

Shared letters muted; letters that set underline and underlined apart highlighted. Shared run: 9.

9 ch
underline
10 ch
underlined

Grammar separator: underline vs underlined

Our dataset has no pronunciation recorded for both members, so the reliable separator here is grammatical: underline is anoun and underlinedaverb. On the page they differ by 1 extra letter(s) - “underline” sits inside “underlined”. Our composite confusion score for this pair is 55503, 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/. underlined is at rank #25,629, tagged as averb.

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 55503, this pair ranks #133,151 of 530,003 scored English confusable pairs - among the most confusable pairs.

Orthographic DNA of underline vs underlined

Shared letters: deilnru. Private to "underline": -. Private to "underlined": -.

"underline" · 9 letters · shape VCCVCCVCV  ·  "underlined" · 10 letters · shape VCCVCCVCVC

Known mistypes of this pair

  • underlinenuderline · udnerline · undderline · undelrine · underilne · underlien · underlinne · underlline
  • underlinednuderlined · udnerlined · undderlined · undelrined · underilned · underliend · underlinde · underlinedd

Frequently Asked Questions

Is swapping "underline" for "underlined" ever safe?
No - they are not even the same part of speech. "underline" is a noun and "underlined" a verb, so a sentence built for one is usually ungrammatical with the other.
Which is more common, "underline" or "underlined"?
"underlined" is the more common of the two: it sits at frequency rank #25,629 in our English list, against #29,874 for "underline". The two are close in frequency, so neither is a safe default; check the meaning rather than guessing.

After this comparison

Done with this confusable. These links stay specific to "underline" and "underlined".

  • Full dictionary entry for "underline" with definition, IPA, and generated misspellings. Word entry
  • Full dictionary entry for "underlined" - compare definitions side by side with the headword page. Word entry
  • This pair ranks #133,151 of 530,003 scored English confusable pairs in this corpus vintage. Corpus statistics
  • "underline" and "underlined" 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 #133,151 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