medium, moderate, or average in size, quantity, or quality: The returns on such a large investment may be only middling. mediocre; ordinary; commonplace; pedestrian: The restaurant's entrées are no better than middling.

What is a middling family?

the "middle" family.

What does middling power mean?

In international relations, a middle power is a sovereign state that is not a great power nor a superpower, but still has large or moderate influence and international recognition. The concept of the "middle power" dates back to the origins of the European state system.