1. Also called wheeler. a horse, or one of the horses, harnessed behind others and nearest the front wheels of a vehicle.
2. Chiefly South Atlantic States.the left-hand horse of a pair hitched to a wagon or plow.
3. Chiefly South Midland and Southern U.S.a reliable, diligent, and strong worker. Also,wheel'-horse".
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.