Argument By Prestigious Jargon
Also "argument by gibberish" :-D
using big complicated words so that you will seem to be an expert.
"Fortifying the dextrose coherence leads to applicable inherence of explicable tolerance, therefore, we should not accept this proposal."
Why do people use "utilize" when they could utilize "use"?
"Bad Subjects, both the publication and the electronic mailing list, are certainly not alone in decrying the over-use of jargon and problems associated with 'difficult' 'overly intellectual' or 'obscure' language. In these venues, when jargonistic language isn't exposed as a cover-up for stupidity, or vacuousness, it has been labelled elitist and self-defeating."
-- Bad subjects
Prestigious jargon is not in itself a logical fallacy. Some people really can't express themselves with simple and clear language and some people are so used to use certain words they use them everywhere.
It is only a fallacy if the speaker chooses words she thinks the opponent doesn't understand, to confuse the opposition, or if difficult words are used to dazzle the opponent or/and the audience, and make the speaker look intelligent and as if she knows what she is talking about.