M1 Meaning of M1 in English M1 BrE AmE ˌem ˈwʌn § -ˈwɒn ▷ M25 ˌem ˌtwent i ˈfaɪv !!-ˌtwen i- AmE -ˌtwen t̬ i-▷ M40 ˌem ˈfɔːt i AmE \ -ˈfɔːrt̬ i —and similarly for other British motorway numbers Longman Pronunciation English Dictionary. Английский словарь произношений Longman. 2012