The only reason Latin is still used by doctors and lawyers is that, as a dead language, it has ceased to evolve and the words mean the same now as they did a thousand years ago. And as it isn't in daily use they should continue to mean the same in another thousand years, unlike English and other languages which see new words formed and the meanings of existing words alter - e.g.

Word Now means Used to mean
"Gay" Poof Happy
"Wicked" Great Bad
"Mobile" Cellphone Dangly thing above a baby's bed

Can you think of any more