ploughbeam
/ˈplaʊbiːm/noun
The central longitudinal beam or bar of timber, iron, etc., in a plough, to which the other principal parts are attached.
Origin
Middle English; earliest use found in Glossary of W. de Bibbesworth. From plough + beam. Compare Middle Dutch ploechboom, Middle Low German plōchbōm, plūchbōm.