Ad Daaarr

Ḍarr is harm — the plain word for damage done. The same root gives ḍurr, distress, and iḍṭurra, to be forced by need, which is the word behind the Qur’an’s allowances for a person with no choice left.

The written form is not in the Qur’anic text; the name comes down in the list, where it is never printed apart from an-Nāfiʿ. What the Qur’an does say with these letters is that nothing else can do either one — no harm and no benefit from anything you might call on besides Him. That the two are held together in one list is the point of the pairing.