The annulus of the tree was clearly visible in the cross-section of the trunk.
In mathematics, a region bounded by two concentric circles.
The area of the annulus can be calculated by subtracting the area of the smaller circle from the area of the larger circle.
In anatomy, a ring-like structure or part, such as the annulus fibrosus in the spine.
The annulus fibrosus is a crucial component of the intervertebral disc, providing structural support.
In botany and mycology, a ring of tissue or membrane encircling or attached to an organ, such as the ring on the stipe of a mushroom or the belt of cells around a fern sporangium.
The mushroom's annulus was wide and white, hanging like a delicate skirt around the stem.