Just in the last four years, I've noticed that the word prior is increasingly used in place of before. Prior has become customary enough that people commonly leave off 'to' in employing it: "Most of the guests appeared at 8:00, but I arrived prior."
I don't know why this disturbs me so, but it does. My question to the linguists, though, is why it's happening now (in North America, anyway.) Both are two syllable words, both convey the same message, more or less -what's driving this change?