وَوُجُوهٌ يَوْمَئِذٍۭ بَاسِرَةٌ
Wa wujoohuny yawma 'izim baasirah
and on that day other faces will be darkened,
Bāsira has a single occurrence, this one, while the verb behind it belongs to the surah immediately before, where a man frowns and scowls as he makes up his mind against the recitation. The same expression is put on a face here, on the day that decision is answered. The word names the tightening itself and leaves the reason to the line that follows.