Which to use
“simultaneous” is an adjective and “simultaneously” is an adverb - they look or sound alike but fill different roles in a sentence.
- #14,414
- “simultaneous” frequency rank
- #5,454
- “simultaneously” frequency rank
- 19868
- confusion score
Side-by-Side Comparison
| Feature | simultaneous | simultaneously |
|---|---|---|
| Definition | Happening at the same moment. | Occurring at the same time. |
Where the eye mixes simultaneous and simultaneously
Muted = shared; highlighted = the visual trap. They share 12 letters in sequence.
Visual trap between simultaneous and simultaneously
These two trip readers on the page rather than in the ear: simultaneous is /ˌsɪm.əlˈteɪ̯.ni.əs/ while simultaneously is /ˌsɪmlˈteɪnɪəsli/. Spoken aloud the problem disappears. In writing it persists, because they differ by 2 extra letter(s) - “simultaneous” sits inside “simultaneously”, and the parts of speech differ too (adjective vs adverb), which is usually the fastest check. Our composite confusion score for this pair is 19868, derived from the frequency rank of both members and their visual similarity.
simultaneous is recorded at frequency rank #14,414, classified as anadj, pronounced /ˌsɪm.əlˈteɪ̯.ni.əs/. simultaneously is at rank #5,454, tagged as anadv, pronounced /ˌsɪmlˈteɪnɪəsli/.
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 19868, this pair ranks #435,160 of 530,003 scored English confusable pairs - a relatively easy-to-tell-apart pair.
Orthographic DNA of simultaneous vs simultaneously
Shared letters: aeilmnostu. Private to "simultaneous": -. Private to "simultaneously": y.
"simultaneous" · 12 letters · shape CVCVCCVCVVVC · "simultaneously" · 14 letters · shape CVCVCCVCVVVCCV
Known mistypes of this pair
- simultaneous ← ismultaneous · simlutaneous · simmultaneous · simulatneous · simulltaneous · simultaenous · simultaneosu · simultaneouss
- simultaneously ← ismultaneously · simlutaneously · simmultaneously · simulatneously · simulltaneously · simultaenously · simultaneosuly · simultaneoulsy
Frequently Asked Questions
Do "simultaneous" and "simultaneously" mean the same thing in a sentence?
Frequency check: "simultaneous" vs "simultaneously" - which ranks higher?
What to do next
Visual near-miss handled. Browse the word pages or a neighbour when the next look-alike shows up.
- Full dictionary entry for "simultaneous" with definition, IPA, and generated misspellings. Word entry
- Full dictionary entry for "simultaneously" - compare definitions side by side with the headword page. Word entry
- This pair ranks #435,160 of 530,003 scored English confusable pairs in this corpus vintage. Corpus statistics
- 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 #435,160 of 530,003 scored English pairs, corpus vintage 2026-09-03, not spelling advice.