新月
The noun 新月 (xīnyuè) means "new moon" or "crescent moon," referring to the lunar phase when the moon is barely visible or appears as a thin sliver. It is used in both scientific and poetic contexts. For example, 新月的时候 means "during the new moon."
今晚是新月,天空很暗。
Jīnwǎn shì xīnyuè, tiānkōng hěn àn.
Tonight is a new moon, so the sky is very dark.
新月的时候几乎看不到月亮。
Xīnyuè de shíhou jīhū kàn bú dào yuèliang.
During a new moon, the moon is almost invisible.
他喜欢在新月的夜晚观测星星。
Tā xǐhuan zài xīnyuè de yèwǎn guāncè xīngxing.
He likes to observe the stars on new moon nights.