Today is Good Friday, the day on which Christians commemorate the crucifixion and death of Jesus Christ. The name may seem counterintuitive to many Christians and nonbelievers, since the day is typically viewed as a solemn one, often observed with fasting and somber processions. Why is Good Friday calledGood Friday?

Probably because good used to mean holy. There are a few theories about why Good Friday is called Good Friday, but only one seems to be supported by linguists and by historical evidence.

The first of these theories is that Good Friday is called Good Friday because, Christians believe, there is something very good about it: It is the anniversary, they say, of Jesus suffering and dying for their sins. “That terrible Friday has been called Good Friday because it led to the Resurrection of Jesus and his victory over death and sin and the celebration of Easter, the very pinnacle of Christian celebrations,” the Huffington Post suggests. Perhaps this logic has helped the name stick—it is certainly how many Christians today understand the name—but it is not where the name originally comes from.

The second theory is that the Good in Good Friday derives from God or “God’s Friday.” Wikipedia, for example, puts this theory forward citing a 1909 entry inThe Catholic Encyclopedia. In a separate article on the same subject, theHuffington Post does the same. However, there seems to be no basis for this etymology. “The origin from God is out of the question” according to Anatoly Liberman, a professor at the University of Minnesota who studies the origins of English words. (Liberman also told me that English speakers have a long history of speculating about a relationship between the word good and the word godwhere there is none.) The linguist and lexicographer Ben Zimmer agreed, noting that the German for Good Friday isn’t actually “Gottes Freitag” (“God’s Friday”), as the Catholic Encyclopedia suggests, but rather Karfreitag (“Sorrowful Friday”). “None of the early examples in the Oxford English Dictionary imply that it started off as God’s rather than Good, so I don’t really see this as more than speculative etymology,” Zimmer added.

The third and final theory, the one supported by both the Oxford English Dictionary 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 onceGood Wednesday, the Wednesday before Easter, which these days is more commonly known as Holy Wednesday.