Anything rotary has a circular form, like an old-fashioned phone. A rotary is also a traffic circle.
Just as the Earth rotates around the sun, rotary objects move in a circle or orbit. A rotary telephone has a circular dial that turns, and a rotary mower has a cutting blade that moves in a circular motion. A type of street where traffic flows in a circle — sometimes called a roundabout — can also be called a rotary. The word stems from the Latin word rotarius, "pertaining to wheels," from its root word rota, or "wheel."