The word "tunneler" can be defined as someone who digs tunnels or someone who navigates tunnels. Some common synonyms for tunneler include miner, digger, underground worker, and excavator. Other synonyms include burrower, mole, and rodent. The term "sapper" also refers to someone who digs tunnels, typically for military purposes. Additionally, the word "spelunker" describes someone who explores and navigates underground caves and tunnels. These synonyms convey a sense of expertise and skill in subterranean excavation, highlighting the important and specialized work done by tunneler professionals.