v.1. To move backward through some region, especially in a vehicle: We backed down the driveway.
2. To cause something, especially a vehicle, to move backward through some region or space: I slowly backed the truck down the hill.
3. To withdraw from a position or confrontation, especially due to intimidation: The smaller bear kept growling so loudly that the larger bear backed down and walked away. Even though they appeared to have a very strong argument against me, I wouldn't back down, and I eventually showed them their conclusions were wrong.