DIPHTHONGAL Meaning of DIPHTHONGAL in English diphthongal BrE AmE ( ˌ ) dɪf ˈθɒŋ ɡ ə l ( ˌ ) dɪp- AmE \ -ˈθɔːŋ- -ˈθɑːŋ- ▷ diphthongal|ly i Longman Pronunciation English Dictionary. Английский словарь произношений Longman. 2012