operculum
/əʊˈpɜː.kjʊ.ləm/
"operculum" is a 9-letter English headword indexed on PlainSpell.
The verdict
“operculum” is uncommon English (frequency #77,980 among 1,431 “O” headwords), classed as a noun. The kind of spelling people second-guess.
- #77,980
- frequency rank, English
- 1,431
- “O” headwords
According to Wiktionary data (CC BY-SA, analyzed September 3, 2026) - A covering flap in animals, such as a gill cover.
Corpus desk
Index EN-operculum · operculum · English
operculum · rank #77,980 · 0 variants · 0 confusables
- FREQ-RARE #77,980
- LEN-LONG 9 letters
- VOW-4 4 vowels
- CONFUS-0 No pairs
- VAR-0 0 variants
- BOOK-MID 1,431
- PHOTO-FINISH oopsie
Nearest frequency peer: oopsie (-1 rank slots)
Read with this headword: Spelling guide for this pattern
Desk codes from Wiktionary headword shape, FrequencyWords rank tier, confusable-pair count, generated misspelling depth, letter-cohort book size, and photo-finish peer. Not a difficulty grade.
Long-tail ranks near “operculum”
Sparse band: bars invert rank so rarer forms read shorter
- officiant
officiant
22,028 corpus weight
- Oklahoman
Oklahoman
22,026 corpus weight
- ontop
ontop
22,023 corpus weight
- oopsie
oopsie
22,022 corpus weight
- operculum
operculum
22,021 corpus weight
- overstock
overstock
22,015 corpus weight
What this shows Long-tail view: where “operculum” sits against similarly uncommon English ranks.
| Property | Value |
|---|---|
| Headword | operculum |
| Language | English |
| Part of speech | Noun |
| IPA | /əʊˈpɜː.kjʊ.ləm/ |
| Letters | 9 |
| Frequency rank | #77,980 |
| Misspellings tracked | 0 |
| Confusable pairs | 0 |
| Source | Wiktionary (kaikki.org) |
Long-tail rank of “operculum” in English
Rare enough to double-check
operculum is uncommon English at frequency #77,980 among 1,431 “O” headwords, classed as anoun, transcribed /əʊˈpɜː.kjʊ.ləm/. Rarity is why readers land here mid-draft. 5 senses are on record.
operculum doesn't appear in our generated misspelling index, and the word's spelling is regular enough that our generator found nothing worth flagging. It is not paired with a close-neighbour confusable in our dataset, since no other headword is close enough in sound or shape to pair with it.
Etymologically, the entry records: Borrowed from Latin operculum. The correct English form is operculum, spelled O-P-E-R-C-U-L-U-M.
Definition
- 1A covering flap in animals, such as a gill cover.
- 2The lidlike portion of a moss sporangium or of a fruit that detaches to allow the dispersal of spores or seeds.
- 3A gum flap covering (part of) a partially erupted tooth, usually a wisdom tooth.
- 4A structure which serves as a cover or lid.
- 5One of several flaps of cerebral cortex covering the insula.
Recorded use
Wiktionary examplesThese source excerpts show how operculum appears in context. They illustrate usage; the definition above remains the entry’s reference meaning.
Hyoliths […] have a small, conical calcium carbonate shell, with a lid called an operculum.
I lifted the circular operculum from its place and laid it carefully on the bale.
Etymology
Borrowed from Latin operculum.
This word in other languages
Definitions, pronunciation, and etymology for this entry are drawn from Wiktionary via the kaikki.org structured extract (CC BY-SA); frequency ordering uses the FrequencyWords open word-frequency list (2018 English corpus, MIT). See the methodology for how each field is sourced and updated.
Frequently Asked Questions
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Similar English words by spelling shape
Same letter count and similar misspelling depth for "operculum", not the corpus desk frequency band.
Same letter count
Frequency-ranked English headwords with 9 letters (nearest by frequency rank).