A ring; a ringlike part or space.

A space contained between the circumferences of two circles, one within the other.

The solid formed by a circle revolving around a line which is the plane of the circle but does not cut it.

Ring-shaped structures or markings, found in, or upon, various animals.

The donut-shaped space around the outside of the drill pipe in an open borehole. A cased well has two annular spaces: one between the drill pipe and the casing, the other between the casing and the borehole.

Downhole space between drillstring or casing and borehole wall, or between production tubing and casing, or between surface casing and production tubing and casing.

Free space between the existing pipe and any lining.

n: the space around a pipe in a well bore, sometimes termed the annular space.

In a rolling element bearing, the space between the inner and outer raceways

This is the tough fibrous outer capsule of an intervertebral disc. In the healthy state it encloses and retains the nucleus.

a two-dimensional shape which can be thought of as a disc with a smaller disc removed from its center

(annulus fibrosis): tough fibrous outer wall of an intervertebral disc.