bad, evil
惡 centers on moral wrongness: something bad, wicked, or evil. It is the traditional form of 悪, carrying the same core idea of negative moral quality.
惡 combines 亞 (originally a pictograph of a vault or complex structure, later associated with 'second' or 'inferior') with 心 (heart/mind), suggesting a twisted or inferior heart leading to badness or evil.
The top 亞 looks like a twisted, complex structure, and the bottom 心 is the heart. Imagine a heart tangled in a crooked, inferior framework — that twisted heart produces bad and evil thoughts.
For アク, picture an evil act: act -> アク, and the twisted heart in 惡 drives someone to commit that bad act.