Correct spelling for the English word "uncommon" is [ʌnkˈɒmən], [ʌnkˈɒmən], [ʌ_n_k_ˈɒ_m_ə_n] (IPA phonetic alphabet).
Not usual; rare; not often seen or known.
Etymological and pronouncing dictionary of the English language. By Stormonth, James, Phelp, P. H. Published 1874.
* The statistics data for these misspellings percentages are collected from over 15,411,110 spell check sessions on www.spellchecker.net from Jan 2010 - Jun 2012.
The word uncommon originated from the combination of two words: un and common. The prefix un- is a negation, meaning not. The word common is derived from the Latin word communis, which means shared or general. Thus, uncommon can be broken down to not common or not shared.