曜

A phono-semantic compound:

日 — sun, light (semantic element)

翟 — sound "yào" (also conveys brilliance), phonetic element

The combination expresses radiance emitted from a heavenly body.

Seal script (篆書): clearly shows 日 combined with 翟

Clerical → regular script: strokes became denser, emphasizing brilliance and motion.

翟 originally depicts feathers shimmering; paired with 日, it intensifies the idea of vivid shining rather than mere brightness.

曜 originally meant “to shine” or “to illuminate,” but over time it became most strongly associated with the concept of weekdays (曜日), reflecting the ancient idea of seven celestial bodies marking each day. This comes from the Babylonian concept of the seven luminaries — the Sun, the Moon, and the five visible planets — which influenced East Asia and led to the naming of the seven days of the week.

요일 (曜日) — day of the week

광요 (光曜) — radiant light (literary)

요명 (曜明) — brilliant clarity (classical)

曜 implies active, striking radiance, often:

- celestial,

- authoritative,

- spiritually revealing.

Compared to 明 (clarity, intelligibility), 曜 emphasizes visual brilliance and presence.

Hence its natural fit for:

- astronomy,

- calendars,

- Buddhist metaphors of enlightenment.

Related characters:

明 — bright, clear

光 — light

輝 — dazzling radiance

照 — to illuminate

晃 — glare, shimmer

晟 — bright and flourishing (name usage)

Classical citations:

Han dynasty cosmological texts

「日月有曜，而四時成焉」

“The sun and moon have their radiance, and thus the four seasons are completed.”

Buddhist texts (Mahāyāna sutra usage)

「佛光曜世，破無明暗」

“The Buddha’s light illuminates the world, breaking the darkness of ignorance.”

Here 曜 signifies spiritual illumination, not physical light alone.

Tang poetry diction

「星曜滿天河」

“Stellar lights fill the Milky Way.”

曜 is favored in poetry to suggest dynamic, living brilliance, more vivid than 明.