Definition, Meaning & Synonyms

epicycle

noun

/ˈɛpɪˌsaɪkəl/

Definition

A small circle whose center moves around the circumference of a larger circle.

Examples

The ancient Greeks used the concept of epicycles to describe the planets’ movements.
In Ptolemaic astronomy, an epicycle was used to account for the retrograde motion of planets like Mars.
Despite its complexity, the epicycle model was accepted for many centuries until the heliocentric model was developed.

Meaning

In historical astronomy, it refers to the small circular orbits of a planet that are thought to explain its apparent irregular movements against the background of stars.