Defense is protection against attack or harm. When a castle had high walls and deep moats, those were its defenses against invading armies. When your body fights off a cold, your immune system is mounting a defense against germs.

In sports, defense means preventing the other team from scoring. A soccer goalie playing strong defense stops shots from reaching the net. A basketball team playing tough defense makes it hard for opponents to get open shots. The players focused on stopping the other team are called defenders or, collectively, the defense.

In law, a defense is the argument someone makes to show they're not guilty of a crime, or the legal team that makes that argument. A lawyer might say, “The defense calls its next witness.” The word defendant refers to the person being accused.

Defense also appears in everyday situations. You might come to a friend's defense when someone criticizes them unfairly, speaking up to protect their reputation. When you explain your reasoning after someone questions your decision, you're defending your choice.

The word defensive describes the protective stance itself, but it also describes someone who reacts badly to criticism, immediately making excuses instead of listening. There's a big difference between having a good defense and being defensive.