Preexisting means something that already existed before a particular moment or event. The prefix pre means “before,” so a preexisting condition is one that was there beforehand.

You'll often hear this word in discussions about health insurance. A preexisting condition is a medical problem someone had before they signed up for new insurance, like asthma or diabetes. Insurance companies used to refuse coverage or charge more for preexisting conditions, which created serious problems for people who needed to switch insurance plans.

The word applies to other situations too. If your family moves into a house with preexisting damage, that means the damage was already there when you arrived. You didn't cause it. If a teacher sets up groups for a project and discovers preexisting friendships among certain students, those friendships formed before the project started.

Understanding what was preexisting helps establish a timeline and figure out who's responsible for what. When archaeologists find preexisting structures at a dig site, they know earlier civilizations built them. When you inherit a preexisting problem, you're dealing with something someone else created before you got involved.