Standard Lemma guide

annulus

noun · 11 senses · updated from the 2026-07-25 local source snapshot

Definitions and examples are grouped by meaning. Pronunciation, history, word forms, translations, descendants, synonyms, antonyms, derived terms, and related words appear whenever the source provides them.

Sound

Pronunciation

Each Play button uses your device's default local English voice, or a natural local fallback. The selected voice name appears after playback. This is synthesized speech, not a source recording.

  • Received-Pronunciation: /ˈænjʊləs/
  • General-American: /ˈænjələs/
  • US: Recorded audio is listed in the source snapshot.
  • Received-Pronunciation: /ˈænjʊlaɪ/
  • Received-Pronunciation: /-li/
  • General-American: /ˈænjəlaɪ/
  • General-American: /-li/

1

noun

Meaning 1

A ring- or donut-shaped area, object, or structure.

Definition source: English Wiktionary via Wiktextract

No example sentence was provided for this meaning.

Meaning relationships

Synonyms: none provided

Antonyms: none provided

Narrower terms: torus

2

noun

Meaning 2

A 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.

Definition source: English Wiktionary via Wiktextract

Topics: anatomy, medicine, sciences

No example sentence was provided for this meaning.

Meaning relationships

Synonyms: none provided

Antonyms: none provided

3

noun

Meaning 3

A 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).

Definition source: English Wiktionary via Wiktextract

Topics: astronomy, natural-sciences

No example sentence was provided for this meaning.

Meaning relationships

Synonyms: none provided

Antonyms: none provided

4

noun

Meaning 4

A 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.

Definition source: English Wiktionary via Wiktextract

Topics: biology, botany, natural-sciences

No example sentence was provided for this meaning.

Meaning relationships

Synonyms: none provided

Antonyms: none provided

5

noun

Meaning 5

The membranous remnants of a partial veil which leaves a ring on the stem of a mushroom.

Definition source: English Wiktionary via Wiktextract

Topics: biology, mycology, natural-sciences

No example sentence was provided for this meaning.

Meaning relationships

Synonyms: none provided

Antonyms: none provided

6

noun

Meaning 6

A 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.

Definition source: English Wiktionary via Wiktextract

Topics: biology, ichthyology, natural-sciences, zoology

No example sentence was provided for this meaning.

Meaning relationships

Synonyms: none provided

Antonyms: none provided

7

noun

Meaning 7

The region in a plane between two concentric circles of different radii.

Definition source: English Wiktionary via Wiktextract

Topics: geometry, mathematics, sciences

No example sentence was provided for this meaning.

Meaning relationships

Synonyms: none provided

Antonyms: none provided

8

noun

Meaning 8

Any topological space homeomorphic to the region in a plane between two concentric circles of different radii.

Definition source: English Wiktionary via Wiktextract

Topics: mathematics, sciences, topology

No example sentence was provided for this meaning.

Meaning relationships

Synonyms: cylinder

Antonyms: none provided

9

noun

Meaning 9

In 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.

Definition source: English Wiktionary via Wiktextract

Topics: engineering, natural-sciences, physical-sciences, technology

No example sentence was provided for this meaning.

Meaning relationships

Synonyms: none provided

Antonyms: none provided

10

noun

Meaning 10

(Fungi) a remnant of the partial veil that in mature mushrooms surrounds the stem like a collar

Definition source: Princeton WordNet 3.0

No example sentence was provided for this meaning.

Meaning relationships

Synonyms: skirt

Antonyms: none provided

Broader terms: plant part, plant structure

11

noun

Meaning 11

a toroidal shape

Definition source: Princeton WordNet 3.0

Examples

  • a ring of ships in the harbor
  • a halo of smoke

Meaning relationships

Synonyms: ring, halo, doughnut, anchor ring

Antonyms: none provided

Broader terms: toroid

Narrower terms: fairy ring, fairy circle

History

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.

Across languages

Translations

87 source translations are retained for this English entry.

  • Aragonese: aniello — ring- or donut-shaped area or structure
  • Asturian: aniellu — ring- or donut-shaped area or structure
  • Catalan: anell — ring- or donut-shaped area or structure
  • Corsican: anellu — ring- or donut-shaped area or structure
  • Finnish: kehä — ring- or donut-shaped area or structure
  • Finnish: rinkilä — ring- or donut-shaped area or structure
  • French: anneau — ring- or donut-shaped area or structure
  • Galician: anel — ring- or donut-shaped area or structure
  • German: Ring — ring- or donut-shaped area or structure
  • Irish: annalas — ring- or donut-shaped area or structure
  • Irish: fáinne — ring- or donut-shaped area or structure
  • Italian: anello — ring- or donut-shaped area or structure
  • Latin: anulus — ring- or donut-shaped area or structure
  • Macedonian: пр́стен (pŕsten) — ring- or donut-shaped area or structure
  • Malay: anulus — ring- or donut-shaped area or structure
  • Portuguese: anel — ring- or donut-shaped area or structure
  • Romanian: inel — ring- or donut-shaped area or structure
  • Russian: кольцо́ (kolʹcó) — ring- or donut-shaped area or structure
  • Russian: коле́чко (koléčko) — ring- or donut-shaped area or structure
  • Spanish: anillo — ring- or donut-shaped area or structure
  • Finnish: rengas — ring of fibrous tissue; specifically, such a ring around an opening of a heart valve
  • Finnish: rengas — ring of light in a celestial body, especially when caused by an annular eclipse
  • French: anneau — ring of light in a celestial body, especially when caused by an annular eclipse
  • Navajo: ahééjiichįįʼ — ring of light in a celestial body, especially when caused by an annular eclipse
  • Romanian: coroană solară — ring of light in a celestial body, especially when caused by an annular eclipse
  • Spanish: corona solar — ring of light in a celestial body, especially when caused by an annular eclipse
  • Finnish: annulus — structure surrounding a sporangium (or part of it) which shrinks and causes it to rupture for seed dispersal
  • Finnish: rengas — structure surrounding a sporangium (or part of it) which shrinks and causes it to rupture for seed dispersal
  • Hungarian: annulusz — structure surrounding a sporangium (or part of it) which shrinks and causes it to rupture for seed dispersal
  • Portuguese: annulus — structure surrounding a sporangium (or part of it) which shrinks and causes it to rupture for seed dispersal
  • Arabic: حَلَقَة (ḥalaqa) — remnants of a partial veil which leaves a ring on the stem of a mushroom
  • Arabic: حَلْقَة (ḥalqa) — remnants of a partial veil which leaves a ring on the stem of a mushroom
  • Catalan: anell — remnants of a partial veil which leaves a ring on the stem of a mushroom
  • Chinese Mandarin: 蕈環 /蕈环 (xùnhuán) — remnants of a partial veil which leaves a ring on the stem of a mushroom
  • Dutch: annulus — remnants of a partial veil which leaves a ring on the stem of a mushroom
  • Finnish: annulus — remnants of a partial veil which leaves a ring on the stem of a mushroom
  • Finnish: rengas — remnants of a partial veil which leaves a ring on the stem of a mushroom
  • Finnish: rengasvyöhyke — remnants of a partial veil which leaves a ring on the stem of a mushroom
  • French: anneau — remnants of a partial veil which leaves a ring on the stem of a mushroom
  • Galician: anel — remnants of a partial veil which leaves a ring on the stem of a mushroom
  • German: Annulus — remnants of a partial veil which leaves a ring on the stem of a mushroom
  • Italian: anello — remnants of a partial veil which leaves a ring on the stem of a mushroom
  • Persian: حلقه قارچ — remnants of a partial veil which leaves a ring on the stem of a mushroom
  • Portuguese: anel — remnants of a partial veil which leaves a ring on the stem of a mushroom
  • Spanish: anillo — remnants of a partial veil which leaves a ring on the stem of a mushroom
  • Venetan: aneło — remnants of a partial veil which leaves a ring on the stem of a mushroom
  • Armenian: օղակ (ōġak) — region in a plane between two concentric circles of different radii
  • Basque: koroa zirkular — region in a plane between two concentric circles of different radii
  • Bengali: চাকতি (cakti) — region in a plane between two concentric circles of different radii
  • Catalan: corona circular — region in a plane between two concentric circles of different radii
  • Chinese Mandarin: 環形 /环形 (huánxíng) — region in a plane between two concentric circles of different radii
  • Chuvash: ункӑ (unk̬ă) — region in a plane between two concentric circles of different radii
  • Czech: mezikruží — region in a plane between two concentric circles of different radii
  • Danish: annulus — region in a plane between two concentric circles of different radii
  • Dutch: cirkelring — region in a plane between two concentric circles of different radii
  • Esperanto: ringo — region in a plane between two concentric circles of different radii
  • Estonian: rõngas — region in a plane between two concentric circles of different radii
  • Finnish: annulus — region in a plane between two concentric circles of different radii
  • Finnish: rengasalue — region in a plane between two concentric circles of different radii
  • French: couronne — region in a plane between two concentric circles of different radii
  • German: Kreisring — region in a plane between two concentric circles of different radii
  • Hebrew: טַבַּעַת (tabá'at) — region in a plane between two concentric circles of different radii
  • Hungarian: körgyűrű — region in a plane between two concentric circles of different radii
  • Indonesian: anulus — region in a plane between two concentric circles of different radii
  • Italian: anello — region in a plane between two concentric circles of different radii
  • Italian: corona circolare — region in a plane between two concentric circles of different radii
  • Japanese: アニュラス (anyurasu) — region in a plane between two concentric circles of different radii
  • Latvian: gredzens — region in a plane between two concentric circles of different radii
  • Polish: pierścień kołowy — region in a plane between two concentric circles of different radii
  • Portuguese: coroa circular — region in a plane between two concentric circles of different radii
  • Romanian: coroană circulară — region in a plane between two concentric circles of different radii
  • Romanian: coroană de cerc — region in a plane between two concentric circles of different radii
  • Russian: кольцо́ (kolʹcó) — region in a plane between two concentric circles of different radii
  • Slovene: kolobar — region in a plane between two concentric circles of different radii
  • Spanish: corona circular — region in a plane between two concentric circles of different radii
  • Spanish: annulus — region in a plane between two concentric circles of different radii
  • Spanish: arandela — region in a plane between two concentric circles of different radii
  • Swedish: cirkelring — region in a plane between two concentric circles of different radii
  • Tamil: வட்டவலையம் (vaṭṭavalaiyam) — region in a plane between two concentric circles of different radii
  • Ukrainian: кільце́ (kilʹcé) — region in a plane between two concentric circles of different radii
  • Vietnamese: hình vành khăn — region in a plane between two concentric circles of different radii
  • Finnish: annulus — topological space homeomorphic to the region in a plane between two concentric circles of different radii
  • Finnish: rengasalue — topological space homeomorphic to the region in a plane between two concentric circles of different radii
  • Chinese Mandarin: 環空 /环空 (huánkōng) — in a well: the space between a pipe or tube and any pipe, tube, casing, or sides of a hole surrounding it
  • Danish: annulus — in a well: the space between a pipe or tube and any pipe, tube, casing, or sides of a hole surrounding it
  • Finnish: välitila — in a well: the space between a pipe or tube and any pipe, tube, casing, or sides of a hole surrounding it
  • Finnish: rengasmainen väli — in a well: the space between a pipe or tube and any pipe, tube, casing, or sides of a hole surrounding it
Real reading context

annulus in complete knowledge articles