annulus

名词 annulus:

1. a toroidal shape
   同义词：ring, halo, anulus, doughnut, anchor ring
2. (Fungi) remnant of the partial veil that in mature mushrooms surrounds the lower part of the stem

an.nu.lus

n.（名词）
【复数】 an.nu.lus.es 或 an.nu.li [-lo.]
A ringlike figure, part, structure, or marking, such as a growth ring on the scale of a fish.
环状物：环状物、部分、结构或标志，如鱼鳞上的生长环

A ring or group of thick-walled cells around the sporangia of many ferns that functions in spore release.
环带：蕨类植物孢子囊周围具有释放孢子功能的环或一组细胞壁很厚的细胞
The ringlike remains of a broken partial veil, found around the stipes of certain mushrooms.
菌环：破损菌幕的环状残留部分，在某些洋菇菌柄周围可见
Mathematics The figure bounded by and containing the area between two concentric circles.
【数学】 圆环域：以两个同心圆为界的图形或两圆之间包括的图形

来源：
Latin 3nulus [ring] [diminutive of] 3nus
拉丁语 3nulus [环，环形物] [] 3nus的小后缀