The prefix pre- means “before” or “ahead of time.” When you see it attached to the front of a word, it tells you that something happens before something else.

If you preview a movie, you watch a short clip before the full film comes out. When you preheat an oven, you turn it on before putting food inside so it reaches the right temperature. A premature decision is one made too early, before you have all the information you need.

You'll find pre- in countless words: prehistoric times existed before people started writing down history, preseason training happens before the regular sports season begins, and prenatal care helps mothers and babies before birth. When something is predetermined, it was decided beforehand.

Once you recognize pre- at the start of a word, you've got an instant clue about its meaning. Look for it in your reading and you'll start noticing it everywhere: preschool, prepay, precaution, preface, preorder. Each time, it signals that something is happening first, earlier, or in advance.