Lord Of All wrote:
"Gothmog 'was a son of Melko and the ogress Fluithuin and his name is Strife-and-hatred (...)" In short Gothmog was meant to originally be a son of Melkor, but later Tolkien changed this idear and made him into a Maiar. Therefore only Gothmog's name means 'Son of Melkor' or 'Voice of Melkor'.
Gothmog did not mean 'Son of Melkor' however -- as noted in the first part of your post, where you quoted that it meant 'strife and hatred' in
The Book of Lost Tales. And (just for clarity) Gothmog as meaning 'Voice of Goth (Morgoth), an Orc-name' is from a 1930s wordlist.
In other words (short version): in
The Book of Lost Tales, Qenya
Kosomot, Kosomoko, Gnomish
Gothmog meant 'Strife and hatred', not 'Son of Melkor' -- nor 'Voice of Melkor'
here at least. And these are Elvish names of course.
Later in the 1930s we find Gothmog meaning 'Voice of Goth' and so on. But in the
Etymologies of the later 1930s early 1940s we again find
Gothmog -- according to this text, where we still have not yet reached the Sindarin of
The Lord of the Rings, Gothmog was said to hail from *Gothombauk- from a base MBAW- 'compel, force, subject, oppress.', and GOS-, GOTH- 'dread'.