In searching in Logos (Gold+) I have been unable to find the origin of the term. I found the following on the web.
Good Friday Origins
There are two possible origins for the name "Good Friday". The first may
have come from the Gallican Church in Gaul (modern-day France and
Germany). The name "Gute Freitag" is Germanic in origin and literally
means "good" or "holy" Friday. The second possibility is a variation on
the name "God's Friday," where the word "good" was used to replace the
word "God," which was often viewed as too holy to be spoken aloud.
Does anyone have anything else on this? Thanks for your help.