Sern in UT/463 is a misprint, see VT/42:11
Noldorin
gonn
noun. rock, stone (as a material)
gonn
noun. great stone, rock
gond
noun. rock
gondobar
place name. Stone of the World
gondrafn
noun. hewn stone
gondram
noun. hewn stone
sarn
noun. stone (as a material)
sarn
noun. small stone
Sern in UT/463 is a misprint, see VT/42:11
Another name for Gondolin appearing in the poem “Song of Ælfwine” (LR/100) and in The Etymologies from the 1930s, where it was translated “Stone of the World”, a combination of gonn “stone” and amar “world” (Ety/GOND, MBAR).
Conceptual Development: The name G. Gondobar appeared in the earliest Lost Tales as one of the names of Gondolin with the translation “City of Stone” (LT2/158), a combination of gonn “stone” and -bar “home” (LT2A/Gondolin, LT1A/Eldamar).