in·ev·i·ta·ble / inˈevitəbəl/ • adj. certain to happen; unavoidable: war was inevitable. ∎ inf. so frequently experienced or seen that it is completely predictable: the inevitable letter from the bank.• n. (the inevitable) a situation that is unavoidable.DERIVATIVES: in·ev·i·ta·bil·i·ty / -ˌevitəˈbilitē/ n.in·ev·i·ta·bly / -blē/ adv. inevitably, she turned her experiences into a book.