Clues for the word "ANNULUS"

We've had 5 crossword clues used for this word, and seen it 4 times in crosswords. It was last seen in Guardian Quick crossword on January 01, 2015.

Definition of annulus

n. - A ring; a ringlike part or space.
n. - A space contained between the circumferences of two circles, one within the other.
n. - The solid formed by a circle revolving around a line which is the plane of the circle but does not cut it.
n. - Ring-shaped structures or markings, found in, or upon, various animals.