The kanji 曜 primarily represents "day of the week" or "weekday." It specifically refers to the days of the week as they relate to the celestial bodies believed to influence those days. The core meaning connects the concept of time (days) with astronomical elements.

・On-yomi (音読み): ヨウ (yō) ・Kun-yomi (訓読み): None, it is not used in standalone form.

⚫︎ 月曜日 (getsuyōbi) Translation: Monday (literally "moon day") ⚫︎ 金曜日 (kin'yōbi) Translation: Friday (literally "gold day") ⚫︎ 今週の火曜日 (konshū no kayōbi) Translation: This week's Tuesday (literally "fire day")

The kanji 曜 is a phono-semantic compound (形声文字). The left side is a "radical" (部首) meaning "sun" or "day" (日). The right side is 翟, which phonetically contributes the sound ヨウ (yō) and likely originally referred to a kind of pheasant. Over time, the meaning shifted, incorporating the concept of celestial bodies influencing the days of the week, linking days to planets, sun, and moon.