Concerning etymology, one of the classics would have to be the old chestnut
which goes "Repentance simply means to change your mind, because
etymologically, it comes from 2 words that mean just that!" I have to side
with the usage folk, I'm afraid, because the way METANOIA is employed in
the NT, shows that its meaning is much broader.
The English dictionaries I use sometimes provide etymology, and sometimes
don't. But they define the word with supporting sentences to show how it
has been, and is being used.