The Hebrew adjective akzar (אַכְזָר) means "fierce, savage, cruel" — describing that which shows no mercy and acts with relentless harshness. It appears rarely in the Old Testament but carries strong emotional force when used, typically describing instruments of divine judgment or the nature of enemies.
The word akzar appears in Isaiah 13:9 and Job 41:10 (describing Leviathan). It represents the quality of merciless severity — the opposite of chesed (lovingkindness). In Isaiah 13, God's day of judgment comes "fierce and cruel" against Babylon's wickedness. The theology here is important: God is not cruel in nature, but He is fierce in justice when evil reaches full measure. Simultaneously, akzar describes the enemies God uses as instruments — who are themselves without mercy. The righteous are contrasted with the akzar, for they show compassion (Proverbs 11:17).