1. the sky or heavens, especially when viewed as a tangible thing
Usage: literary
2. the sphere of the fixed stars in ancient astronomy
Usage: archaic; astronomy

Examples

• The stars twinkled in the vast firmament above.
• Ancient sailors navigated by studying the firmament.
• The poet described the moon as a silver coin in the firmament.
• Medieval astronomers believed the firmament was a solid dome.
• She gazed up at the blue firmament on that clear summer day.
• The firmament seemed to stretch endlessly in all directions.