Pronunciation: [ˈʌn fˈɜːmə] (IPA)
Correct spelling for the English word "un firmer" is [ˈʌn fˈɜːmə], [ˈʌn fˈɜːmə], [ˈʌ_n f_ˈɜː_m_ə] (IPA phonetic alphabet).
Correct spelling for un firmer