1. a small circle whose center moves around the circumference of a larger circle, used in ancient astronomy to explain planetary motion
Usage: astronomy; historical
2. a complex or repetitive series of events or activities
Usage: figurative

Examples

• Ptolemy used epicycles to explain the apparent retrograde motion of planets.
• The ancient Greek model included multiple epicycles for each planet.
• Medieval astronomers added more epicycles to improve their calculations.
• The theory of epicycles was eventually replaced by elliptical orbits.
• The company seemed trapped in an epicycle of failed product launches.
• His argument created an epicycle of circular reasoning.