INTERSTITIAL Meaning of INTERSTITIAL in English interstitial BrE AmE ˌɪnt ə ˈstɪʃ ə l ◂ AmE \ ˌɪn t̬ ə r-▷ interstitial|ly i▷ interstitial|s z Longman Pronunciation English Dictionary. Английский словарь произношений Longman. 2012