underliningvsunderlyingWhich spelling fits?

Quick tell: underlining is a verb, underlying is an adjective, so they fill different roles in a sentence.

Which to use

“underlining” is a verb and “underlying” is an adjective - they look or sound alike but fill different roles in a sentence.

#42,468
“underlining” frequency rank
#5,464
“underlying” frequency rank
47932
confusion score

Side-by-Side Comparison

Feature underlining underlying
Definition present participle and gerund of underline lying underneath

Letter map: underlining vs underlying

Shared letters muted; letters that set underlining and underlying apart highlighted. Shared run: 9.

11 ch
underlining
10 ch
underlying

Role in the sentence - underlining and underlying

Our dataset has no pronunciation recorded for both members, so the reliable separator here is grammatical: underlining is averb and underlyinganadjective. On the page they differ by 1 letter(s) in length. Our composite confusion score for this pair is 47932, derived from the frequency rank of both members and their visual similarity.

underlining is recorded at frequency rank #42,468, classified as averb. 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 47932, this pair ranks #197,835 of 530,003 scored English confusable pairs - roughly mid-pack for confusability.

Orthographic DNA of underlining vs underlying

Shared letters: degilnru. Private to "underlining": -. Private to "underlying": y.

"underlining" · 11 letters · shape VCCVCCVCVCC  ·  "underlying" · 10 letters · shape VCCVCCVVCC

Known mistypes of this pair

  • underliningnuderlining · udnerlining · undderlining · undelrining · underilning · underliinng · underlinign · underliningg
  • underlyingnuderlying · udnerlying · undderlying · undelrying · underliyng · underllying · underlyign · underlyingg

Frequently Asked Questions

Do "underlining" and "underlying" mean the same thing in a sentence?
No - they are not even the same part of speech. "underlining" is a verb and "underlying" an adjective, so a sentence built for one is usually ungrammatical with the other.
Which is more common, "underlining" or "underlying"?
"underlying" is the more common of the two: it sits at frequency rank #5,464 in our English list, against #42,468 for "underlining". The two are close in frequency, so neither is a safe default; check the meaning rather than guessing.

What to do next

Done with this confusable. These links stay specific to "underlining" and "underlying".

  • Full dictionary entry for "underlining" 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 #197,835 of 530,003 scored English confusable pairs in this corpus vintage. Corpus statistics
  • "underlining" and "underlying" also get mixed up with nearby pairs, the highest-scored neighbour is "underlining vs underpinning". 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 #197,835 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