An antiseptic is a substance that kills or stops the growth of germs on living tissue, like your skin. When you scrape your knee on the playground, cleaning the wound with an antiseptic helps prevent bacteria from causing an infection. Common antiseptics include rubbing alcohol, hydrogen peroxide, and iodine solutions.

Before antiseptics were discovered in the mid-1800s, even minor surgeries were incredibly dangerous because bacteria would infect wounds and patients could die. A British surgeon named Joseph Lister pioneered the use of antiseptics in hospitals, revolutionizing medicine by dramatically reducing infections and death rates.

Today, antiseptics are everywhere. Doctors wash their hands with antiseptic soap before surgery. Parents keep antiseptic wipes in first aid kits. Hand sanitizer is a type of antiseptic. Notice that antiseptics work on living tissue (like your skin), while similar substances called disinfectants are stronger chemicals used on non-living surfaces like countertops and floors.

The word can also describe something that feels sterile, clean, or emotionless. A hospital room might look antiseptic with its white walls and harsh lighting, meaning it feels clinical and impersonal rather than warm and cozy.