Definitions

1. noun

A rare or obsolete term for a blue-gray colour or a deep blue colour with a slight greenish or purplish tint.

“The artist experimented with different shades of atroceruleus in her latest painting.”

2. adjective

Describing a blue-gray colour or a deep blue colour with a slight greenish or purplish tint.

“The atroceruleus sky reflected the beauty of the ocean at sunset.”