What is this sin in us called? This sin in us is called original.
Why is this sin called original? This sin is called original because it comes down to us through our origin, or descent, from Adam.
Therefore as through one man sin entered into the world and through sin death, and thus death has passed unto all men because all have sinned. (Romans 5:12)
What are the chief punishments of Adam which we inherit through original sin? The chief punishments of Adam which we inherit through original sin are: death, suffering, ignorance, and a strong inclination to sin.
Further reading: CCC 407-409