Which to use
“mucous” is an adjective and “mucus” is a noun - they look or sound alike but fill different roles in a sentence.
- #38,982
- “mucous” frequency rank
- #23,915
- “mucus” frequency rank
- 62897
- confusion score
Side-by-Side Comparison
| Feature | mucous | mucus |
|---|---|---|
| Definition | Pertaining to mucus. | A slippery secretion from the lining of the mucous membranes. |
Same sound, different letters: mucous vs mucus
Muted letters are shared; highlighted letters are the only spelling cue when pronunciation matches. Shared run: 5 letters. mucous runs 6 letters (CVCVVC) against mucus's 5 (CVCVC) - the length gap alone is often enough to separate them once you know to check it.
Ear matches; page differs - mucous and mucus
Say them out loud and nothing separates them: mucous and mucus carry the same recorded pronunciation, /ˈmjuːkəs/. Grammar is what tells them apart: one is anadjective, the other anoun, so most sentences will only accept one of them. They differ by 1 letter(s) in length. Our composite confusion score for this pair is 62897, derived from the frequency rank of both members and their visual similarity.
mucous is recorded at frequency rank #38,982, classified as anadj, pronounced /ˈmjuːkəs/. mucus is at rank #23,915, tagged as anoun, pronounced /ˈmjuːkəs/.
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 62897, this pair ranks #85,974 of 530,003 scored English confusable pairs - among the most confusable pairs.
Orthographic DNA of mucous vs mucus
Shared letters: cmsu. Private to "mucous": o. Private to "mucus": -.
"mucous" · 6 letters · shape CVCVVC · "mucus" · 5 letters · shape CVCVC
Known mistypes of this pair
Frequently Asked Questions
Do "mucous" and "mucus" mean the same thing in a sentence?
In ordinary English text, does "mucous" or "mucus" show up more?
What to do next
Sound matches; spelling doesn't. Use the exits below to lock the right form or check a cousin pair.
- Full dictionary entry for "mucous" with definition, IPA, and generated misspellings. Word entry
- Full dictionary entry for "mucus" - compare definitions side by side with the headword page. Word entry
- This pair ranks #85,974 of 530,003 scored English confusable pairs in this corpus vintage. Corpus statistics
- "mucous" and "mucus" also get mixed up with nearby pairs, the highest-scored neighbour is "mucosa vs mucous". 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 #85,974 of 530,003 scored English pairs, corpus vintage 2026-09-03, not spelling advice.