Sapper/ˈsæpər/ Definition 1 of 3Pro Tip 1/3Military Usage Commonly used in a military context to describe a specialized soldier. A team of sappers arrived to fortify the base. Pro Tip 2/3Historical Roots Originally referred to those who dug trenches in siege warfare. Medieval sappers tunneled under castle walls. Pro Tip 3/3Associated Tasks Sappers perform a variety of tasks including laying or clearing explosives. Sappers were called in to clear the roadside bombs.