DICTIONARY
all words real, definitions with help from dictionary.com
Cantabrigian
adj. of or pertaining to Cambridge (England or Massachusetts)
iff
prep. if and only if (literally pronounced "if and only if", iff has the highest syllable-to-letter ratio of any English word)
mu
interj. "Your question is flawed!", word of Japanese origin used to answer a yes or no question when neither response is accurate
multitudinousness
noun the state of being multitudinous, proof that there can be too many suffixes on one word.
qoph
noun one of the letters of the Arabic alphabet (fun for use in Scrabble)
sesquipedalian
adj. of or pertaining to very long words