Aero- is a prefix that means “air” or “relating to flight.” We use it to build words connected to aviation, the atmosphere, and anything involving the sky.

When you see aero- at the start of a word, think about air or flying. An aerobic exercise class gets its name because it works your body in ways that strengthen your ability to use oxygen from the air. An aerodynamic race car has a shape designed to slip through air with minimal resistance, just like a dolphin's body cuts smoothly through water. Aerospace engineering deals with designing aircraft and spacecraft. An aerosol spray releases tiny particles into the air.

The prefix appears in aeroplane (the British word for airplane) and in the aero bars on racing bicycles, which let riders tuck into positions that reduce air resistance.

Understanding aero- helps you decode unfamiliar words. If you read about an aeronaut, you can guess it means someone who travels through the air, like a pilot or astronaut. When scientists discuss aerosols in Earth's atmosphere, you know they're talking about particles suspended in air.