I was reading a book has an interesting discussion over this word- Jejune. It says that the word has taken a new meaning recently which has no connection to its roots. It says that "jejune" comes from Latin and basically means "dry" or "barren". Hence, it's wrong to use that word to describe a thing or person as childish or naive. However, I checked this word in the dictionaries and all of them has included this definition.
Now, my question is it pompous or pretentious to use "jejune", these days, to mean "uninteresting"? Or does it sound archaic? For instance,
The lecturer's present was insipid, jejune, and long-winded!
Checking the Ngram, I found that it was much more popular in the past, in general.