To Prohibit, To Forbid
transitive verb, ichidan verb
This word consists of kanji with hiragana attached. Because the hiragana ends with an う sound, you know this word is a verb. The kanji itself means prohibition so the verb version means to prohibit or to forbid.
きんじる
This has the same reading as the kanji you learned, meaning you know the reading!
関係者以外の立ち入りを禁じる。
Entry is prohibited to all but related parties.
アルコールは世界で禁じられるべきだと思います。
I think alcohol should be banned worldwide.
この部屋では、私語を禁じます。
Private conversation is prohibited in this room.