The example «غِشَاوَةٌ» occasions an interpretive discussion. On the type-reading, the noun points to a distinctive quality of covering. The *Miftāḥ* also treats the indefiniteness as magnification: an unusually severe or extraordinary covering.
غِشَاوَةٌ عَظِيمَةٌ
A great or severe covering — an explanatory paraphrase, not a quotation from the verse.
These readings should not be conflated. Type highlights the distinctive kind; magnification emphasizes its extraordinary scale or force. They can reinforce each other in context while remaining analytically different.