Which to use
“hydroxy” is an adjective and “hydroxyl” is a noun - they look or sound alike but fill different roles in a sentence.
- #40,288
- “hydroxy” frequency rank
- #42,190
- “hydroxyl” frequency rank
- 82478
- confusion score
Side-by-Side Comparison
| Feature | hydroxy | hydroxyl |
|---|---|---|
| Definition | Being, or containing a hydroxyl radical. | A univalent radical or functional group (–OH) in organic chemistry; present in alcohols, phenols, carboxylic acids and certain other classes of compounds. |
Where the spellings diverge
Shared letters are muted; the letters that actually set hydroxy and hydroxyl apart are highlighted. They share 7 letters in sequence, which is exactly why the eye skips the difference.
Spelling & Dictionary Insight
Our dataset has no pronunciation recorded for both members, so the reliable separator here is grammatical: hydroxy is anadjective and hydroxylanoun. On the page they differ by 1 extra letter(s) - “hydroxy” sits inside “hydroxyl”. Our composite confusion score for this pair is 82478, derived from the frequency rank of both members and their visual similarity.
hydroxy is recorded at frequency rank #40,288, classified as anadj. hydroxyl is at rank #42,190, tagged as anoun.
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 82478, this pair ranks #15,655 of 530,003 scored English confusable pairs - among the most confusable pairs.
Orthographic DNA of hydroxy vs hydroxyl
Shared letters: dhorxy. Private to "hydroxy": -. Private to "hydroxyl": l.
"hydroxy" · 7 letters · shape CVCCVCV · "hydroxyl" · 8 letters · shape CVCCVCVC
Known mistypes of this pair
Frequency comparison
Frequently Asked Questions
Can "hydroxy" and "hydroxyl" be used interchangeably?
Which is more common, "hydroxy" or "hydroxyl"?
Remembering hydroxy vs hydroxyl
The fastest way to pick the right one every time.
- Check the role first: if you need an adjective, it's “hydroxy”; for a noun, it's “hydroxyl”.
- See each word in full, definition, IPA, etymology and its other confusables. Full “hydroxy” entry
- Browse more pairs most likely to be confused. Most confusable