The Hebrew adjective akzari (אַכְזָרִי) means "cruel, merciless, pitiless" — the intensified or extended form of akzar (H393). It describes a quality of sustained, deliberate cruelty without compassion. This word appears in Proverbs and the Psalms to describe wicked men, and in prophetic literature to describe judgments and enemies.
The akzari person in Proverbs 11:17 is contrasted with the kind person: "A man who is kind benefits himself, but a cruel man hurts himself." This reveals the self-destructive nature of cruelty — it corrupts the one who practices it. In Proverbs 12:10, the "kindest acts of the wicked are cruel" — even their apparent mercy is tainted. Theologically, cruelty is the antithesis of the image of God (imago Dei), which is inherently relational and compassionate. God's fierce judgment against cruel nations (Isaiah 13) is itself an expression of His mercy toward the oppressed.