sapper

Etymology

Borrowed from Middle French sappeur (French sapeur). Surface etymology is sap + -er.

noun

1. Historical term for a combat engineer that is still used in some armies, in other words an engineer or a soldier engaged in attacking, destroying, and circumventing or building fortifications, bridges, and roads; a military engineer active in a combat zone.
   his knowledge of Arabic and freedom from the theories of the ordinary sapper-school enabled him to teach the art of demolition to unlettered Beduin in a quick and ready way. 1926, T.E. Lawrence, Seven Pillars of Wisdom, New York: Anchor, published 1991, page 114
2. (Britain, colloquial) An officer or private of the Royal Engineers.
   By a remarkable piece of railway reconstruction work on the part of the Allied Forces—mainly South African railway construction troops—mines laid along the track by the retreating enemy were removed by sappers, and the German damage made good, within 7 days. 1944 March and April, “The Western Desert Railway”, in Railway Magazine, page 73
   Billinge, from St Austell, was one of the first soldiers to land on 'Gold' beach on June 6 1944. He was a sapper attached to the 44 Royal Engineer Commandos and was one of only four to survive from his unit. October 21 2020, “Network News: GWR train naming honours D-Day veteran Harry”, in Rail, page 17