This noun denotes light, especially splendor or radiance—the brightness emanating from heavenly bodies or other sources. It can mean daylight, moonlight, or the luminous quality of shining objects. Classical Greek distinguished phengos (light, radiance) from phōs (light as substance or source), though the terms overlap. The New Testament uses appear in apocalyptic contexts describing the failure or darkening of celestial lights—sun and moon ceasing to give their radiance. The cosmic darkening signals the end of the present order and the arrival of God's direct presence.