Which to use
“radium” and “radius” are a confusable English pair: similar on the page, but distinct in meaning, check the gloss before you choose.
- #37,184
- “radium” frequency rank
- #8,847
- “radius” frequency rank
- 46031
- confusion score
Side-by-Side Comparison
| Feature | radium | radius |
|---|---|---|
| Definition | The chemical element (symbol Ra) with an atomic number of 88. It is a soft, shiny and silvery radioactive alkaline earth metal. | The long bone in the forearm, on the side of the thumb. |
Where the eye mixes radium and radius
Muted = shared; highlighted = the visual trap. They share 5 letters in sequence.
Look-alike desk: radium vs radius
A purely visual mix-up. radium (/ˈɹeɪ.dɪ.əm/) and radius (/ˈɹeɪ.di.əs/) are said differently, so reading them aloud is the quickest way to catch the wrong one. On the page they stay close: they differ by a single letter - m in “radium” becomes s in “radius”. Our composite confusion score for this pair is 46031, derived from the frequency rank of both members and their visual similarity.
radium is recorded at frequency rank #37,184, classified as anoun, pronounced /ˈɹeɪ.dɪ.əm/. radius is at rank #8,847, tagged as anoun, pronounced /ˈɹeɪ.di.əs/.
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 46031, this pair ranks #215,638 of 530,003 scored English confusable pairs - roughly mid-pack for confusability.
Orthographic DNA of radium vs radius
Shared letters: adiru. Private to "radium": m. Private to "radius": s.
"radium" · 6 letters · shape CVCVVC · "radius" · 6 letters · shape CVCVVC
Known mistypes of this pair
Frequently Asked Questions
Can "radium" and "radius" be used interchangeably?
In ordinary English text, does "radium" or "radius" show up more?
Useful next steps
Visual near-miss handled. Browse the word pages or a neighbour when the next look-alike shows up.
- Full dictionary entry for "radium" with definition, IPA, and generated misspellings. Word entry
- Full dictionary entry for "radius" - compare definitions side by side with the headword page. Word entry
- This pair ranks #215,638 of 530,003 scored English confusable pairs in this corpus vintage. Corpus statistics
- "radium" and "radius" also get mixed up with nearby pairs, the highest-scored neighbour is "radium vs Rahim". 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 #215,638 of 530,003 scored English pairs, corpus vintage 2026-09-03, not spelling advice.