وهو أن يدور الحكم مع المعنى المشترك وجودا وعدما
It means that the judgment accompanies the common feature both in presence and in absence.
When the relevant feature is present, the judgment is present; when the feature is absent, the judgment is absent. This two-directional pattern is called dawarān.
The definition demands more than a single coincidence. It requires examination in both positive and negative cases.