Briefly means for a short time or using just a few words. When your teacher asks you to briefly explain your answer, she wants the main point without a long story. When a butterfly lands briefly on a flower, it stays only a moment before flying away.

When you summarize something briefly, you're giving the essential information in a compact way. A student might briefly mention their weekend plans, or a doctor might briefly examine a patient's scraped knee.

Notice that briefly doesn't mean rushed or careless. A scientist can briefly explain a complex discovery clearly and completely, just without extra details. When a news reporter covers a story briefly, she still includes the important facts. Learning to speak and write briefly takes practice: you need to figure out which details matter most and which ones you can leave out.

The opposite would be speaking at length, going on and on, or taking forever to make your point. When something happens briefly, like a brief rain shower, it's over quickly.