Crescent Moon
New Moon
noun
What's "third day moon"? It's crescent moon. Crescent moon is the new moon that appears on the third day of the month in the lunar calendar that Japanese people used back in the day.
The word comes from 三日 and 月, but the readings are slightly different. There's no small つ in the reading for 三日, and you need to rendaku 月, all to make it easier to pronounce. Try reading it aloud yourself to see what I mean!
To write the character づ, type "du" on your keyboard.
今日は三日月です。
There's a crescent moon today.
三日月のような目をしてますね。
You have eyes that are like a crescent moon.
山の上から三日月がよく見える。
You can see the crescent moon well from the top of the mountain.