Lexicological analysis
The word زُبُر zubur (in Al-Qamar 54:43 ⧉) is the plural of zabur, which stands for any written book. It specifically refers to the Scripture that was revealed to Prophet Dawud (علیہ السلام) .
أَدْهَىٰ وَأَمَرُّ (...more calamitous and more bitter...Al-Qamar 54:46 ⧉). The word adha means more or most calamitous. The word amarr is derived from murr which originally means 'bitter'. By extension anything 'difficult' or 'painful' is also referred to as amarr and murr. In the phrase فِي ضَلَالٍ وَسُعُرٍ fi dalalin wa su'ur, dalal, as is known, means 'error' or 'deviation' and the word su'ur in the present context means the 'Hell-Fire1.' In the phrase ashya'akum, (Al-Qamar 54:51 ⧉) ashya` is the plural of shi'ah, and it means a 'follower', that is, those who follow their pattern of life.
(1). This is according to one interpretation. The other meaning of the word is 'madness' and the translation in the text is based on this meaning. (Muhammad Taqi Usmani
In the phrase مَقْعَدِ صِدْقٍ maq` adi-sidqin, the word maq'ad means 'seat' and the word sidq means 'truth' and implies the 'seat of truth' where there will be no idle and obscene talks.