Which to use
“prolong” is a verb and “prolonged” is an adjective - they look or sound alike but fill different roles in a sentence.
- #22,183
- “prolong” frequency rank
- #9,513
- “prolonged” frequency rank
- 31696
- confusion score
Side-by-Side Comparison
| Feature | prolong | prolonged |
|---|---|---|
| Definition | To extend in space or length. | Lengthy in duration; extended; protracted. |
Where the eye mixes prolong and prolonged
Muted = shared; highlighted = the visual trap. They share 7 letters in sequence.
Why the eye confuses prolong with prolonged
These two trip readers on the page rather than in the ear: prolong is /pɹəʊˈlɒŋ/ while prolonged is /pɹəʊˈlɒŋd/. Spoken aloud the problem disappears. In writing it persists, because they differ by 2 extra letter(s) - “prolong” sits inside “prolonged”, and the parts of speech differ too (verb vs adjective), which is usually the fastest check. Our composite confusion score for this pair is 31696, derived from the frequency rank of both members and their visual similarity.
prolong is recorded at frequency rank #22,183, classified as averb, pronounced /pɹəʊˈlɒŋ/. prolonged is at rank #9,513, tagged as anadj, pronounced /pɹəʊˈlɒŋd/.
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 31696, this pair ranks #344,013 of 530,003 scored English confusable pairs - roughly mid-pack for confusability.
Orthographic DNA of prolong vs prolonged
Shared letters: glnopr. Private to "prolong": -. Private to "prolonged": de.
"prolong" · 7 letters · shape CCVCVCC · "prolonged" · 9 letters · shape CCVCVCCVC
Known mistypes of this pair
Frequently Asked Questions
Do "prolong" and "prolonged" mean the same thing in a sentence?
Frequency check: "prolong" vs "prolonged" - which ranks higher?
Useful next steps
Eye-level mix-up between "prolong" and "prolonged" is sorted above. Next: full entries or other pairs that share a letter shape.
- Full dictionary entry for "prolong" with definition, IPA, and generated misspellings. Word entry
- Full dictionary entry for "prolonged" - compare definitions side by side with the headword page. Word entry
- This pair ranks #344,013 of 530,003 scored English confusable pairs in this corpus vintage. Corpus statistics
- "prolong" and "prolonged" also get mixed up with nearby pairs, the highest-scored neighbour is "prolong vs prowling". 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 #344,013 of 530,003 scored English pairs, corpus vintage 2026-09-03, not spelling advice.