A plank, bar, log, or the like, especially one of a pair, on which something heavy may be slid or rolled along. (Dictionary.com)
One of a number of such logs or timbers forming a skid way.
A low mobile platform on which goods are placed for ease in handling, moving, etc. (Dictionary.com)
If a vehicle skids, it slides sideways or forwards while moving, for example when you are trying to stop it suddenly on a wet road. (Collins Dictionary)
One of a group of objects (such as planks or logs) used to support or elevate a structure or object. (Merriam – Webster)
What is a skid?
Skid steer and track loaders.