As video-streaming services are becoming more common the benefit of multicast transmission is growing, because multicast is more bandwidth efficient than unicast in scenarios where many receivers simultaneously are interested in the same data. Of the same reason the concept of multicast fairness is starting to attract attention, it might be sensible to give multicast flows higher priority and thereby create an incentive for the use of multicast transmission. Allocating link bandwidth in proportion to the logarithm of the number of receivers of a flow, which favors multicast flows without totally starving unicast flows, has been proposed in [Bandwidth-allocation policies for unicast and multicast flows]. That was however just as a bandwidth-allocation policy ran on the individual routers and not a definition of multicast fairness. To our knowledge no one has yet come up with a definition of multicast fairness which prioritizes multicast flows. In this paper we present a general multicast-fairness definition, named multicast-favorable max-min fairness (MFMF), which can be used together with any multicast-favorable function.