This was a Roman praenomen, or given name, used predominantly by the Claudia family. Its etymology is unknown. A famous bearer of this name was Appius Claudius Caecus, a Roman statesman of the 3rd century BC. He was responsible for the Aqua Appia (the first Roman aqueduct) and the Appian Way (a road between Rome and Capua), both of which were named for him.
There were no related names found for Appius.