Middle Primitive Elvish
sam
root. unite, join
sambē
noun. *chamber
stabnē
noun. wooden post
stabnō
noun. carpenter, wright, builder
stambē
noun. room, chamber
ala-
prefix. very
dag
root. dig
pheleg
root. cave
rǭda
noun. cave
stabrō
noun. carpenter, wright, builder
A rejected root in The Etymologies of the 1930s glossed “dig” (Ety/DAG), it may have been a transient replacement for √SAP.