مانع يمنع تمامها
An impediment that prevents a cause from reaching completion.
There may be an initial legally meaningful basis, but the required duration, constituents or evidentiary steps have not all been satisfied. A subsequent event prevents the legal ground from becoming complete.
The distinction from the first type is critical: in the first, the cause cannot be constituted at all; in the second, an initiated basis fails to reach the required completeness. Loss of qualifying zakat wealth during the year and failure of a necessary witness are the text's illustrations.