• مُبْلِسُون
• يُبْلِسُ

Appears 5 times in the Quran.

1. 6:44 فَلَمَّا نَسُوا۟ مَا ذُكِّرُوا۟ بِهِۦ فَتَحْنَا عَلَيْهِمْ أَبْوَٰبَ كُلِّ شَىْءٍ حَتَّىٰٓ إِذَا فَرِحُوا۟ بِمَآ أُوتُوٓا۟ أَخَذْنَٰهُم بَغْتَةً فَإِذَا هُم مُّبْلِسُونَ

   But when they neglected that with which they had been admonished, We opened for them the doors of all things, until when they rejoiced in what they were given We seized them suddenly; then lo! they were in utter despair.
   

2. 23:77 حَتَّىٰٓ إِذَا فَتَحْنَا عَلَيْهِم بَابًا ذَا عَذَابٍ شَدِيدٍ إِذَا هُمْ فِيهِ مُبْلِسُونَ

   Until when We open upon them a door of severe chastisement, lo! they are in despair at it.
   

3. 30:12 وَيَوْمَ تَقُومُ ٱلسَّاعَةُ يُبْلِسُ ٱلْمُجْرِمُونَ

   And at the time when the hour shall come the guilty shall be in despair.
   

4. 30:49 وَإِن كَانُوا۟ مِن قَبْلِ أَن يُنَزَّلَ عَلَيْهِم مِّن قَبْلِهِۦ لَمُبْلِسِينَ

   Though they were before this, before it was sent down upon them, confounded in sure despair.
   

5. 43:75 لَا يُفَتَّرُ عَنْهُمْ وَهُمْ فِيهِ مُبْلِسُونَ

   It shall not be abated from them and they shall therein be despairing.