FIRE!
Yelling fire will undoubtedly disturb everyone in the vicinity from what they are doing.
Thus, it is the most disturbing word. Similarly 'HELP!' or 'STOP!' when yelled would be good candidates for this riddle.
The most commonly used word in English is the word 'the'.
The most common word in the English language is the word the.
Diddled
Seriously? In England (where the word 'English' comes from), English is the language of choice.
the c word: c*unt
hello
Cu*t
in
Because most of the United States speak English and are English men.
mother
it is used to translate a word from the Italian language to the English language most dictionaries are typically in the vice/versa
spammers