One of the OT's three primary sin words (alongside chatta'ah H2403 and pesha H6588), avon focuses on the crooked nature of sin — a twisting or perversion of what should be straight. It often carries both the sin itself and its resulting guilt or punishment, showing that wrongdoing carries built-in consequences.
The three sin words often appear together for total coverage: 'forgiving iniquity (avon), transgression (pesha), and sin (chatta'ah)' (Ex 34:7). Avon emphasizes the moral distortion — sin is not just rule-breaking but the warping of one's character and direction. Isaiah 53 uses it of the Servant bearing 'our iniquities' — taking the twisted burden we should carry.