During my first semester of grad school long ago, I took a Physical Organic class. It was a great class. The teacher was from Poland and spoke with a moderate accent, not thick enough to be indecipherable, but occasionally some words were totally different.
One day we were talking about diastereomers. Now, for the non-chemists out there, I'm not going to try to explain it. It would take more time that I want. For those of you who need refresher, Eliel defines diastereomers as: "Stereoisomers that are not related as mirror images. They usually differ in physical and chemical properties."
The correct (or at least most understood) pronunciation is: die'-ah-stair'-e-o-merz. OK, not the way Webster would have written it, but you get the point. Well, on day in class, my Polish prof pronounced it: dee-ah'-stur-oh'-murs (note the accent on the second syllable). Say it out loud. It sounds quite different than the "normal" way of saying it.
We were in class when this happened and it took a few minutes to figure out what he was saying. Yet, since we were familiar with diastereomers, we eventually figured it out.
However, this prof also taught Sophomore level Organic Chemistry. The students in that class had never heard of diastereomers before. As a result, the class of about 300 all learned to pronounce it as dee-ah'-stur-oh'-murs. It was hilarious to have a student come to the chemistry help center and ask for help on "dee-ah'-stur-oh'-murs" from the TA. I wonder how many of them still pronounce it wrong.