spiral
A curve that is the locus of a point that rotates about a fixed point while continuously increasing its distance from that point.
Other meanings
A self-sustaining process with a lot of momentum involved, so it is difficult to accelerate or stop it at once.
A section of track that forms a circle and crosses over itself, used for gaining height in mountainous territory.
Word history
From Ancient Greek "σπεῖρα" (wreath, coil, twist).
Where this comes from
This definition is adapted from “spiral” on Wiktionary, by its contributors, published under CC BY-SA 4.0. This page is published under the same licence.