Annulus
/ˈæn.jə.ləs/noun
A ring-shaped structure or object, especially one forming the space between two concentric circles.
Did you know?Annulus comes from Latin anulus, a diminutive of anus meaning “ring”; the same Latin word also gave English the anatomical term anus.
Etymological Timeline
Classical Latin
Latin
ānulus
“A ring or little ring; a diminutive of ānus, “ring.””
Late Latin
Latin
annulus
“A ring, circular band, or ring-shaped form.”
17th Century
New Latin
annulus
“A mathematical ring-shaped region between two concentric circles.”
17th–18th Century
English
annulus
“A ring-shaped object or structure, especially in geometry and anatomy.”
Modern English
English
annulus
“A ring-shaped structure, including the region between concentric circles.”