Definition of annulus
plural an·nu·liplay \-ˌlī, -(ˌ)lē\ also an·nu·lus·es
1 : ring
2 : a part, structure, or marking resembling a ring: as a : a line of cells around a fern sporangium that ruptures the sporangium by contracting b : a growth ring (as on the scale of a fish) that is used in estimating age
Origin of annulus
Medieval Latin, from Latin anulus finger ring, from anus ring — more at anus
First Known Use: 1563
Learn More about annulus
Medical Dictionary: Definition of "annulus"
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