Excellent news, word fans!  I now have a subscription to the Oxford English Dictionary on line.  I’m learning oodles and oodles about its features.  Most important of all, I have learned the difference between obsolete and archaic words as the OED classifies them.  Obsolete words have not been spotted by the OED folks in about 100 years.  Archaic words are formerly common, now headed toward obsolescence.  Rare words are a different category.  Clearly, any word in a published work by Professor Tolkien can’t be obsolete but sometimes he uses an obsolete meaning of an otherwise in-use word.  The great news for me is that the OED will declare whether a word is archaic, or a meaning is obsolete. I will not be eyeballing trends in the Google Ngram Viewer and making a judgement call.  Also, I have learned how to cite each word look-up.