I wouldn't call it multiple inheritance, because when looking at other languages, this can be very confusing. In languages like C++ multi inheritance describes inheritance of multiple classes including functionality, there are no interfaces (i.e. only signatures no functionality). Other languages like Go don't have inheritance in the classical sense, but still has interfaces.
In the context of Pascal, you could call it multiple inheritance "lite" (as there is no functionality as is with class inheritance), but I would just call it what it is, just a description of the promised functionality of a class