To inoculate someone means to give them a vaccine or similar treatment that protects them from disease. When a doctor inoculates you against measles or tetanus, they're introducing a weakened or inactive form of the germ into your body so your immune system learns to fight it off. It's like giving your body a practice round before facing the real threat.

This dangerous technique, called variolation, eventually led to the development of safer vaccines. Edward Jenner's smallpox vaccine in 1796 made inoculation much safer and helped lead to smallpox being completely eliminated from the world.

The word has expanded beyond medicine. Teachers might inoculate students against misinformation by teaching them critical thinking skills. Parents might try to inoculate their children against peer pressure by building their confidence early. In these cases, inoculation means preparing someone in advance to resist something harmful.

The related word inoculum refers to the substance used in inoculation, while an inoculation is the act itself or the shot you receive.