What is meant by "darkness" (ẓulumāt) in this verse?

Imām Ibn al-Jawzī (d. 597 AH / 1201 CE) summarized the scholars' opinions in his book "Zād al-Masīr" as follows:

1. Punishment. [Ibn ʿAbbās]
2. Disbelief. [Mujāhid]
3. A darkness that Allah casts upon them after death. [Qatāda]
4. Their hypocrisy. [Al-Suddī]