Very Nice...
Once again I've been trumped.

#20 PZB polarizable.... tsuwm 11 letters better than my 12 letter hypnotizable

#9 JZT jazziest..... that's the same word I had

#4 GFM while engulfment is a good one (10 letters), I still have an 8 letter word, and you seem to be on the right track with your comment.

While finding the longest word was mentioned as part of the game, I prefer finding the shortest words for the very reason that you demonstrated with "polarizability." It seems one can always append another suffix or two to generate a longer "acceptable" English word.