We have a number of etymology-related questions that seem rather difficult to answer authoritatively. Here are a few examples of what I'm talking about:
- What underlying semantic notions connect 'studere' to 'to put in, put aside, spare, keep'?
- What underlying semantic notions explain the etymology of 'pravus'?
- What (if anything) does the prefix 'de-' mean in *defallere?
I'd like to know if authoritative resources exist that address these types of questions. The reason I am skeptical is that I have not found anything relevant for studere, pravus, or defallere in Michiel de Vaan's Etymological Dictionary of Latin, but of course many other resources may exist.
The reason I ask is that without sources, it seems like all we can do is make educated guesses (as I did in an answer to the last of these three). If such speculation is all that is available, I wonder if the questions are approaching "primarily opinion based" territory.