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. |
Letter map: hydroxy vs hydroxyl
Shared letters muted; letters that set hydroxy and hydroxyl apart highlighted. Shared run: 7. hydroxy runs 7 letters (CVCCVCV) against hydroxyl's 8 (CVCCVCVC) - the length gap alone is often enough to separate them once you know to check it.
Grammar separator: hydroxy vs hydroxyl
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
Frequently Asked Questions
Do "hydroxy" and "hydroxyl" mean the same thing in a sentence?
Frequency check: "hydroxy" vs "hydroxyl" - which ranks higher?
What to do next
Pair "hydroxy" vs "hydroxyl" is on the table, pick a follow-up below.
- Full dictionary entry for "hydroxy" with definition, IPA, and generated misspellings. Word entry
- Full dictionary entry for "hydroxyl" - compare definitions side by side with the headword page. Word entry
- This pair ranks #15,655 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 #15,655 of 530,003 scored English pairs, corpus vintage 2026-09-03, not spelling advice.