Warning
Admonition
noun, verbal noun
My instruction is my commandment. You must do what I say in my instructions/commandments. This is my warning. This is my admonition.
This is a jukugo word that uses the on'yomi readings of the kanji. You should be able to read this on your own.
いつも勉強会で居眠りする同僚がいてさ、ついに上司が今日それについて訓戒を与えてたよ。
My coworker always dozes off during study sessions and our boss finally admonished him for it today.