v.1. To move backward out of some region: The bear backed out of the cave.
2. To move or drive something backward out of some region: The sergeant backed the tank out of the trench. We picked up the heavy sofa and slowly backed it out of the living room and onto the porch.
3. To decide not to keep a commitment or promise: They backed out of the deal at the last minute. We had a plan to finish the work together, but they backed out.