brightness; splendor; radiance
Refers to a brilliant, shining light or glory, often with a poetic or formal tone. Used for literal light, as well as metaphorical brilliance of achievements or character.
The jewel gave off a brilliant radiance.
The brightness of the sun filled the room.
彼の功績は永遠の光輝を放つだろう。
His achievements will shine with eternal splendor.
彼の生涯は光輝に満ちていた。
His life was filled with splendor.
光彩 emphasizes colorful, dazzling light or luster, whereas 光輝 emphasizes pure, glorious brightness.
栄光 refers specifically to glory or honor earned through achievement, while 光輝 can describe either literal shining light or a more general sense of splendor.
好機 (a good opportunity) and 光輝 (brightness, splendor) are pronounced identically as こうき but have completely unrelated meanings.
Compound of 光 (light) and 輝 (radiance), both kanji carrying meanings of brightness and shining. The reading こうき is the on'yomi for both characters.