lockspit1
/ˈlɒkspɪt/noun
A narrow trench dug to mark out a boundary or to indicate lines of work in construction or civil engineering projects.
Origin
Mid 17th century; earliest use found in Exemplification St Ives Law Sewers. Apparently from either lock or lock + spit.
lockspit2
/ˈlɒkspɪt/verb
[with object] To mark out (a line or boundary) by digging a lockspit or trench.
Origin
Late 17th century. From lockspit.