月曜日
げつようび · getsuyoubi · JLPT N5 · noun
Monday
🌙 月曜日 = moon + weekday: Moon-day, just like English Mon(moon)day
月 (getsu) is moon, 曜日 (youbi) is day of the week. English Monday is also literally Moon-day, so the two languages match piece for piece. Every weekday ends in the same youbi, so only the first kanji changes.
月 — pictograph of crescent moon
月 is a pictograph of a crescent moon, chosen over a full circle to distinguish it from 日 (sun). The inner strokes originally depicted the moon's shadow or markings. As a radical it often relates to the moon, time, or (via a lookalike form of 肉 'flesh') body parts.
日 — pictograph of the sun
日 is a pictograph of the sun, originally drawn as a circle with a dot or stroke inside representing the sun's substance. Over time the round shape was squared off into the modern rectangular form. It means 'sun' and by extension 'day'.