Rotary means moving in a circle around a central point, like a wheel turning on its axle. A rotary phone has a dial that spins in a circle when you use it to make a call. A rotary engine has parts that spin rather than move back and forth like the pistons in a car engine.

Think of how a pottery wheel rotates as the potter shapes clay, or how a rotary fan blade spins to push air around a room. When something has rotary motion, it turns continuously around a fixed center point.

You might also encounter rotary as a noun meaning a traffic circle, where cars drive around a central island instead of stopping at a traditional intersection. In some places these are called roundabouts. The idea is the same: instead of crossing straight through, traffic flows in a rotating pattern.

Rotary International, a famous service organization, takes its name from the early practice of rotating meeting locations among members' offices. The name reminds us that rotary doesn't just describe physical spinning: it can mean any system where things take turns moving through a cycle.