Deadly Offense is a term used to describe a type of attack or strategy that is particularly dangerous and effective. The term can be broken down into two parts: Deadly, meaning something that is capable of causing death or great harm, and Offense, meaning an attack or strategy. The crossword solution for the term Deadly Offense is SIN, which stands for Serious Injury or Negligence. This term is often used in legal contexts to refer to an act that has caused serious injury or death due to negligence.