Any luminous or colored ring that encircles something.
A circle of light or halo around the head of a deity or a saint.
A corona.
A ring around an igneous intrusion.
The rim (of a ring) within which a jewel is set.
A band, flange, ferrule, or collar, designed to grip and hold a tool or a workpiece under proper control, and usually to release it under control thereafter; such a collet usually is made of a hard, springy material, especially a metal.
In an embryonic plant, the transition zone between the root and the hypocotyl (not clearly distinguishable in most plants.)