annulus
/ˈænjʊləs/noun
(pl. annuli /-laɪ/)
1- technical a ring-shaped object, structure, or region〈技〉环形物; 环形结构; 环带。
1.1
- Mathematics a plane figure consisting of the area between a pair of concentric circles【数】圆环。
词源
mid 16th cent.: from Latin anulus, annulus.