Tyranny
Outrage, Atrocity, Cruel
noun, な adjective
Violence and oppression are all signs of tyranny and that someone is being really cruel.
This is a jukugo word that uses the on'yomi readings of the kanji. You should be able to read this on your own.
あいつらは暴虐の限りを尽くしたんだ。
They committed all kinds of tyrannical acts.