Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
aurīgo, āvi, ātum, 1 (aurīgor, āri, v. dep., Varr. ap. Non. p. 70, 17), v. n. [auriga], to be a charioteer or a contender in the chariot-race, to drive a chariot, to contend in the chariot-race.