Sunset
noun
At night the sun dies at sunset. Don't worry, it will be reborn tomorrow morning at sunrise and everything will be okay.
にちぼつ
This is a jukugo word that uses the on'yomi readings of the kanji. You should be able to read this on your own.
今出発すれば、日没までには着けると思います。
If I leave now I think I can arrive by sunset.