A verb appearing as {dal- >>} dol- “dig” in the Gnomish Lexicon of the 1910s derived from the early root ᴱ√ndolo (GL/30). This root was glossed “delve” in the contemporaneous Qenya Lexicon (QL/65).
Gnomish
saptha-
verb. to dig, bite into
dol-
verb. to dig
A verb appearing as G. saptha- “to dig, to bite into” in the Gnomish Lexicon of the 1910s based on the early root ᴱ√SAPA “dig, excavate” (GL/67).
Neo-Sindarin: The root √SAP reappeared in Tolkien’s later writings, but for purposes of Neo-Sindarin I would adapt G. saptha- as a basic verb ᴺS. sab- “to dig” to avoid questions of how its phonetics would have changed in later Sindarin.