What is the most difficult English word to pronounce?

for me its "massachusetts"

well , it`s based on the organs of speech you may face problems in using them in some pronunciation. let`s say the words that have consonant cluster of3 to7 consonants such as the word , sixths. This word ends with four-letters consonant cluster, so it`s , somehow , hard for some people to pronounce it fluently.

Well, not one only.....

there is some medical word  , and complicated term

It has a personal factor, cultural (mother language) factor, and mental-syntactic factor as well.

I believe that for different people will be different words. For me is  otorhinolaryngologist

is really a hard one. :)  Many of my students mispronounce the word 'kitchen' as 'chicken'. :P so i think really it depends on the person trying to say the words:P

otorhinolaryngologist

It all depends

Its depend on the candidates..

depends one the mother language

Rollerblading

Miscellaneous

Deterioration

Tremendous