Meaning 1 It may describe an omitted نَفْس: no person will be a denier or liar regarding its occurrence.
Meaning 2 It may carry the sense of impeding or slowing down, leading to the meaning: no holding it back.
كَذَبَ in Arabic can be used in the sense of something dropping in strength, failing in its normal function, or losing intensity. From this, the sense of slowing, preventing, or impeding is connected.
Two basic senses mentioned - To say something one knows is not true.
- To say something false, even if one believes it, closely tied to denial.
Day of Judgement implication There will be liars of both kinds: one who knew truth and called it false, and one who believed lies instead of truth. But when الْوَاقِعَةُ descends, nobody remains able to persist in that state.