Declaration
Noun and する verb
せんげん
彼のお気に入りのアイドルが、年末に引退するって宣言したから、彼も他のファンもショックを受けちゃってるのよ。
His favorite idol shocked him and other fans by announcing that she will retire at the end of this year.
You proclaim things by saying them. This is a proclamation or declaration.
This is a jukugo word that uses the on'yomi readings of the kanji. You should be able to read this on your own.