Toroids

Part of speech: noun

Definitions

1. A three-dimensional geometric shape similar to a doughnut that has a circular cross-section and a hollow center
2. An object characterized by a central hole or cavity that is encircled by a continuous surface
3. A ring-like structure in mathematics and physics that is formed by revolving a circle around an axis external to the circle's own plane

Etymology: "Toroids" is simply the plural of "toroid," so it carries the same story as its singular. The base word comes from "torus," the Latin term for a swelling or cushion-like bulge, which is also the source of the architectural "torus," a rounded moulding on a column base. Mathematicians and physicists adopted the Latin form for the donut-shaped surface or solid generated by spinning a circle around an axis lying outside it, and "toroid" adds the suffix "-oid," from Greek "eidos," meaning "form" or "resemblance," to signal a shape that resembles a torus without necessarily being exactly one.