1. Sports.
   1. A competition of speed, as in running or riding.
   2. races A series of such competitions held at a specified time on a regular course: a fan of the dog races.
2. An extended competition in which participants struggle like runners to be the winner: the presidential race.
3. Steady or rapid onward movement: the race of time.
4. 1. A strong or swift current of water.
   2. The channel of such a current.
   3. An artificial channel built to transport water and use its energy. Also called raceway.
5. A groovelike part of a machine in which a moving part slides or rolls.
6. See slipstream (sense 1).

1. Sports. To compete in a contest of speed.
2. To move rapidly or at top speed: We raced home. My heart was racing with fear.
3. To run too rapidly due to decreased resistance or unnecessary provision of fuel: adjusted the idle to keep the engine from racing.

1. Sports.
   1. To compete against in a race.
   2. To cause to compete in a race: She races horses for a living.
2. To transport rapidly or at top speed; rush: raced the injured motorist to the hospital.
3. To cause (an engine with the gears disengaged, for example) to run swiftly or too swiftly.

[Middle English ras, from Old Norse rās, rush, running.]

The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved.