WordNet (r) 3.0 (2006):

taxidriver
    n 1: someone who drives a taxi for a living [syn: taxidriver,
         taximan, cabdriver, cabman, cabby, hack driver,
         hack-driver, livery driver]

Moby Thesaurus II by Grady Ward, 1.0:

22 Moby Thesaurus words for "taxidriver":
   Sunday driver, backseat driver, bus driver, busman, cabby,
   cabdriver, chauffeur, driver, hack, hackdriver, hackman, hacky,
   hit-and-run driver, jitney driver, joyrider, motorist, road hog,
   speeder, teamster, truck driver, trucker, truckman