A safeguard is something that protects against harm, danger, or problems. Think of it as a safety measure you put in place before trouble starts. When you wear a helmet while biking, the helmet is a safeguard against head injuries. When a bank requires two passwords to access an account, that second password is a safeguard against theft.

Safeguards work by preventing bad things from happening in the first place, or by reducing damage if something does go wrong. A smoke detector is a safeguard in your home. The rules against running in the hallways at school are safeguards against collisions and injuries.

You can also use safeguard as a verb, meaning to protect something. A library might safeguard rare books by keeping them in a special, temperature-controlled room. Parents safeguard their children by teaching them to look both ways before crossing the street.

Good safeguards often seem unnecessary until you actually need them. The fire extinguisher in your kitchen might sit unused for years, but when a grease fire starts, that safeguard becomes incredibly important.