annulus
/ˈænjʊləs/
"annulus" is a 7-letter English headword indexed on PlainSpell.
The verdict
“annulus” is an uncommon English word, ranked #69,641 in English word frequency and used as a noun.
- #69,641
- frequency rank, English
- 7
- letters
According to Wiktionary data (CC BY-SA, analyzed May 6, 2026) - A ring- or donut-shaped area, object, or structure.
| Property | Value |
|---|---|
| Headword | annulus |
| Language | English |
| Part of speech | Noun |
| IPA | /ˈænjʊləs/ |
| Letters | 7 |
| Frequency rank | #69,641 |
| Misspellings tracked | 0 |
| Confusable pairs | 0 |
| Source | Wiktionary (kaikki.org) |
Where “annulus” sits in English frequency
Spelling & Dictionary Insight
The English entry for annulus is 7 letters long, classified as a noun, and transcribed in the International Phonetic Alphabet as /ˈænjʊləs/. Corpus data places it at rank #69,641 in overall English word frequency, marking it as uncommon enough that many writers pause before typing it. Wiktionary records 9 distinct senses for this headword, so context determines which meaning a reader should apply.
No misspelling variants are generated for annulus in our index, since its letter pattern doesn't lend itself to common typo substitutions. No confusable counterpart is on file for this word, a sign it's visually distinctive enough not to be mixed up with another word.
Etymologically, the entry records: Learned borrowing from Medieval Latin ānnulus, a misspelling of Latin ānulus (“ring, especially one worn on a finger”), from ānus (“ring”) (possibly from Proto-Indo-European *h₁eh₂-n-o- (“ring”), from an uncertain root) + -ulus (diminutive suffix). The plur… The correct English form is annulus, spelled A-N-N-U-L-U-S.
Definition
- 1A ring- or donut-shaped area, object, or structure.
- 2A ring of fibrous tissue; specifically (cardiology), such a ring around an opening of a heart valve, to which the valve leaflets and muscle fibres of the atria and ventricles are attached; an annulus fibrosus cordis.
- 3A ring of light in a celestial body, especially when caused by an annular eclipse (for example, when the Sun and Moon are in line with the Earth, but the Moon does not completely cover the Sun's disc).
- 4A structure surrounding a sporangium (or part of it) which shrinks and causes it to rupture for spore dispersal; specifically, in a fern: a structure around about two-thirds of the sporangium consisting of differentially thick-walled cells which dry and distort the sporangium; and in a moss: a complete ring of cells around the tip of the sporangium which dissolves to cause the tip to detach.
- 5The membranous remnants of a partial veil which leaves a ring on the stem of a mushroom.
- 6A dark ring on a fish's scale that is formed when a fish's growth rate slows down in the winter due to low food intake and the scale's circuli move closer to one another. The dark ring is used to estimate the fish's age, approximately one year per annulus.
- 7The region in a plane between two concentric circles of different radii.
- 8Any topological space homeomorphic to the region in a plane between two concentric circles of different radii.
- 9In a well such as an oil well or water well: the space between a pipe or tube and any pipe, tube, casing, or sides of a hole surrounding it.
Etymology
Learned borrowing from Medieval Latin ānnulus, a misspelling of Latin ānulus (“ring, especially one worn on a finger”), from ānus (“ring”) (possibly from Proto-Indo-European *h₁eh₂-n-o- (“ring”), from an uncertain root) + -ulus (diminutive suffix). The plural form annuli is a learned borrowing from Medieval Latin ānnulī.
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.
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Using “annulus”
The practical upshot for anyone who landed here from a spell-check.
- The one correct English spelling is A-N-N-U-L-U-S - every other letter order is a misspelling in standard orthography.
- Say it as /ˈænjʊləs/ (IPA); tap the speaker on the pronunciation badge to hear it where audio exists.
- Browse more English words and confusable pairs in the same reference. English words
Data Source
Wiktionary (via kaikki.org), licensed under CC BY-SA & GFDL. Word ordering uses an open word-frequency list; misspelling variants are generated by edit-distance from the correct headword.