racer

Short definition from Wiktionary

Noun

1. 1
   Someone who takes part in a race.
2. 2
   A racehorse.
3. 3
   A vehicle or other device used for, or designed specifically for, racing.
4. 4
   An animal known for its fast speed, or suitable for racing; applied especially to a number of North American snakes, certain kinds of lake trout, etc.
5. 5
   Any of several genera of colubrid snakes.
6. 6
   A video game involving racing of any kind.
7. 7
   Racist.

Proper noun

1. 1
   A surname from German.