三日月
みかづき · mikaduki · JLPT N2 · noun
moon
🌙 三日月 = three + day + moon: the thin crescent seen about 3 days after new moon
三日月 literally means three-day moon. Around day three of the lunar cycle, the moon shows only as a thin curved sliver, which is why it is called a crescent.
三 — three horizontal strokes 一 + 一 + 一
三 is a pictographic numeral: three stacked horizontal lines representing the number three, parallel to 一 (one) and 二 (two). The form has been stable since oracle bone script. It carries no phonetic component; the meaning 'three' is direct and visual.
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'.
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.