rotary

American  

[roh-tuh-ree] / ˈroʊ tə ri /

adjective

1. turning or capable of turning around on an axis, as a wheel.

2. taking place around an axis, as motion.

3. having a part or parts that turn on an axis, as a machine.

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noun

plural

rotaries

1. a rotary device or machine.

2. Chiefly Northeastern U.S. traffic circle.

3. Also called rotary converter.  Electricity. synchronous converter.

4. (initial capital letter) Rotary Club.

rotary British  

/ ˈrəʊtərɪ /

adjective

1. of, relating to, or operating by rotation

2. turning or able to turn; revolving

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noun

1. a part of a machine that rotates about an axis

2. a roundabout (for traffic)

Other Word Forms

• unrotary
  adjective

Etymology

Origin of rotary

1725–35; < Medieval Latin rotārius (adj.), equivalent to Latin rot ( a ) wheel + -ārius -ary

Explanation

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."

Example Sentences

That’s prompted more companies to take a fresh look at old combustion tech, including the rotary engine, and figure out new ways for gas power and battery power to work together.

From The Wall Street Journal • Apr. 26, 2026

A startup called LiquidPiston has spent more than a decade developing a new kind of rotary engine—including the X Mini shown here—that it says can be both more efficient and compact than traditional piston engines.

From The Wall Street Journal • Apr. 24, 2026

LiquidPiston’s Shkolnik says that someday, his company’s novel rotary engine could be ideal for providing range extension.

From The Wall Street Journal • Apr. 24, 2026

A birthday kid from Long Island phoning his father on one of the rotary phones in the lobby.

From The Wall Street Journal • Mar. 13, 2026

Inside is an old-fashioned rotary phone that has played an unusual role in helping many move on after the disaster.

From "Meltdown" by Deirdre Langeland