cruel: unmoved by another person's suffering, and unwilling to let up
Hebrew names this quality mostly by what is missing. Jeremiah describes an oncoming army twice with the same pair of statements: the enemy "is cruel" and "will not show mercy." The word pictures less someone who enjoys inflicting pain than someone who cannot be reached by another person's pain, who has heard the pleading and will not soften.
Proverbs sets it directly opposite kindness. The kind man does himself good while the cruel man wrecks his own flesh (Proverbs 11:17), and even the compassion of the wicked counts as cruelty (Proverbs 12:10), because at their gentlest they still wound. The word is a verdict on what a person is, not a report on one bad mood.
The prophets widen it past individuals:
- an invading army that rides in and gives no quarter (Jeremiah 6:23; 50:42)
- a punishment that falls with nothing held back (Jeremiah 30:14)
- the day of the LORD itself, arriving with wrath and burning anger (Isaiah 13:9)
In each case the point is the same: nothing is going to call this off partway.
A shorter word of the same family (אַכְזָר) covers much of the same ground while reaching further, to things and creatures as well as people. One verse uses the naming form of this word, "cruelty" (אַכְזְרִיּוּת), for the quality on its own.