The word(s) "lighten" appears 16 time(s) in 16 verse(s) in Quran in Abdullah Yusuf Ali translation.

(11) And if they reject thee, so did their predecessors, to whom came their messengers with Clear Signs, Books of dark prophecies, and the Book of Enlightenment.

(12) But those who reject (Allah) - for them will be the Fire of Hell: No term shall be determined for them, so they should die, nor shall its Penalty be lightened for them. Thus do We reward every ungrateful one!

(13) Is one whose heart Allah has opened to Islam, so that he has received Enlightenment from Allah, (no better than one hard-hearted)? Woe to those whose hearts are hardened against celebrating the praises of Allah! they are manifestly wandering (in error)!

(14) Those in the Fire will say to the Keepers of Hell: "Pray to your Lord to lighten us the Penalty for a day (at least)!"

(15) Nowise will the (Punishment) be lightened for them, and in despair will they be there overwhelmed.

(16) And its enlightenment as to its wrong and its right;-