1. a group or set of nine things or people
Usage: formal or technical; often used in mathematics, philosophy, or classical studies
2. in Neoplatonic philosophy, a group of nine divine principles or emanations
Usage: specialized; historical philosophy

Examples

• The ennead of planets in ancient astronomy included the Sun and Moon.
• Plotinus organized his philosophical system into an ennead of fundamental principles.
• The composer created an ennead of short pieces for solo piano.
• In mathematics, an ennead can refer to any collection of nine elements.
• The ancient Egyptians recognized an ennead of major deities.