Pseudo-intellectual. A clear communicator uses the simplest, precise word that has the precise meaning they intend, reaching most commonly for the Germanic vocabulary unless they need the subtler shades of meaning from the Latinate. A pseudo-intellectual uses Latinate vocabulary to conceal what they're actually saying or to intimidate people who aren't as comfortable on the Latinate side of the fence. It's a form of intellectual bullying that, to my mind, makes the person using it look insecure (not to mention likely dishonest).

A good communicator's motto should be "eschew gratuitous obfuscation (see what I mean?)".