Which to use
“rational” is an adjective and “rationally” is an adverb - they look or sound alike but fill different roles in a sentence.
- #6,511
- “rational” frequency rank
- #26,220
- “rationally” frequency rank
- 32731
- confusion score
Side-by-Side Comparison
| Feature | rational | rationally |
|---|---|---|
| Definition | Capable of reasoning. | In a rational manner |
Letter map: rational vs rationally
Shared letters muted; letters that set rational and rationally apart highlighted. Shared run: 8.
Part-of-speech tell for rational / rationally
Our dataset has no pronunciation recorded for both members, so the reliable separator here is grammatical: rational is anadjective and rationallyanadverb. On the page they differ by 2 extra letter(s) - “rational” sits inside “rationally”. Our composite confusion score for this pair is 32731, derived from the frequency rank of both members and their visual similarity.
rational is recorded at frequency rank #6,511, classified as anadj, pronounced /ˈɹæʃ(ə)nəl/. rationally is at rank #26,220, tagged as anadv.
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 32731, this pair ranks #335,380 of 530,003 scored English confusable pairs - roughly mid-pack for confusability.
Orthographic DNA of rational vs rationally
Shared letters: ailnort. Private to "rational": -. Private to "rationally": y.
"rational" · 8 letters · shape CVCVVCVC · "rationally" · 10 letters · shape CVCVVCVCCV
Known mistypes of this pair
- rational ← artional · raitonal · ratinoal · ratioanl · rationall · rationla · rationnal · ratoinal
- rationally ← artionally · raitonally · ratinoally · ratioanlly · rationallyy · rationaly · rationalyl · rationlaly
Frequently Asked Questions
Is swapping "rational" for "rationally" ever safe?
Frequency check: "rational" vs "rationally" - which ranks higher?
Useful next steps
You've compared "rational" and "rationally". Here's where to go from here.
- Full dictionary entry for "rational" with definition, IPA, and generated misspellings. Word entry
- Full dictionary entry for "rationally" - compare definitions side by side with the headword page. Word entry
- This pair ranks #335,380 of 530,003 scored English confusable pairs in this corpus vintage. Corpus statistics
- "rational" and "rationally" also get mixed up with nearby pairs, the highest-scored neighbour is "rationally vs regionally". 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 #335,380 of 530,003 scored English pairs, corpus vintage 2026-09-03, not spelling advice.