Definition of annulus in English:

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Pronunciation: /ˈanjʊləs/

noun (plural annuli /ˈanjʊlʌɪ/ /ˈanjʊliː/)

1A ring-shaped object, structure, or region.
Example sentences
  • Channel incorporation was typically achieved within a few minutes after ‘brushing’ the membrane fraction across the annulus with fresh lipids to form a new bilayer.
  • The tympanic annulus must be completely visible.
  • The fibrillar collagens also change across the disc, with the nucleus containing only type II collagen while both types I and type II are found in the annulus.
1.1 Mathematics A plane figure consisting of the area between a pair of concentric circles.
Example sentences
  • A theorem is proved that delineates criteria for the radii of the annulus of the zeros in the complex plane of the generating function for factorial moments as it applies to high-energy charged-hadron multiproduction.
  • In this case, weighting was used to adjust for the fact that at increasing distances from a seed there will be an increasing number of possible maternal trees simply due to the greater two-dimensional area of an annulus of a fixed width.
  • In this paper, we find necessary and sufficient conditions for the stability of a family of annular, complex polynomials with the possibility of including a center polynomial. The proposed results can be modified to solve the disk problem by simply equating the inner radius of the annuli to zero.


Mid 16th century: from Latin anulus, annulus.

For editors and proofreaders

Line breaks: an¦nu|lus

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