Secondary means second in order, importance, or development. When something is secondary, it comes after or matters less than something primary or main.

In school, elementary students move on to secondary school (middle school and high school) as the second major stage of their education. A book's secondary characters support the main character but aren't the focus of the story: in Charlotte's Web, Templeton the rat is a secondary character compared to Wilbur and Charlotte.

The word also describes something that results from or depends on something else. If you slip on ice and sprain your ankle, the sprain is the primary injury. But if you then can't practice for your soccer game and your team loses, that loss becomes a secondary consequence of your fall.

When doctors talk about secondary symptoms, they mean effects that stem from the main illness rather than the illness itself. If you have the flu (primary) and then develop an ear infection because your body was weakened (secondary), that's a secondary infection.

People sometimes say an issue is of secondary importance when it matters, but other things matter more right now. If you're studying for a major test tomorrow, cleaning your room might be of secondary importance: you'll do it later, but the test comes first.