Wicked, evil, or morally corrupt; having a cruel or malicious nature.
Compound adjective from dark (used metaphorically for evil) + hearted (from heart, the organ considered the seat of emotions). Uses 'dark' as a symbol for evil, ancient in Western thought.
The metaphor 'dark heart' for evil is so old and widespread that we barely notice it—but it shows how humans have connected darkness with badness and light with goodness for thousands of years across almost every culture.
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