Over at slate.com Forrest Wickman cites three explanations for why we refer to Good Friday as “Good.” Here’s his conclusion:
The third and final theory, the one supported by both the Oxford English Dictionary [OED] and every language expert I contacted, is that the name comes from an antiquated meaning of good. “The answer seems pretty clearly to be that it’s from good ‘holy,’ ” responded Jesse Sheidlower, the president of the American Dialect Society, when I put this question to him. Liberman agreed, noting that if you consider the other names for Good Friday—“Sacred Friday” in the Romance languages (Viernes Santo, e.g.), “Passion Friday” in Russian—“the OED’s explanation makes excellent sense.” The OED also notes that there was once Good Wednesday, the Wednesday before Easter, which these days is more commonly known as Holy Wednesday.
That explanation also encourages me in my use of “Holy Thursday” instead of “Maundy Thursday.”
Link to the original article: http://slate.me/1q6rBkA