You can find seven meanings mentioned in OED's entry for the word greatest, amongst which can be labelled obsolete. See ‘This means & use’ for definitions, usage, and quotation proof. It had been the longest solitary—in runtime—to reach the top British charts at that time, As well as in 2013, https://thegreatestsongever10752.daneblogger.com/35057590/top-what-is-the-greatest-song-ever-secrets