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 spellings diverge
Shared letters are muted; the letters that actually set simultaneous and simultaneously apart are highlighted. They share 12 letters in sequence, which is exactly why the eye skips the difference.
Spelling & Dictionary Insight
simultaneous and simultaneously form a confusable pair in the English index, two distinct headwords that are easily confused because they look alike, sound alike, or both. They differ by 2 extra letter(s) - “simultaneous” sits inside “simultaneously” - close enough that the eye skips over the difference, far enough that meaning fully diverges. 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.
Frequency comparison
Frequently Asked Questions
Can "simultaneous" and "simultaneously" be used interchangeably?
Remembering simultaneous vs simultaneously
The fastest way to pick the right one every time.
- Check the role first: if you need an adjective, it's “simultaneous”; for an adverb, it's “simultaneously”.
- See each word in full, definition, IPA, etymology and its other confusables. Full “simultaneous” entry
- Browse more pairs most likely to be confused. Most confusable