ف ت رf-t-r
(ن) فَتَرَ يَفْتُرُ فُتُوْرًاfatara yafturu futūran: to subside after speed and intensity, to slacken, to cease. ﴿يُسَبِّحُوْنَ الَّيْلَ وَالنَّهَارَ لَا يَفْتُرُوْنَ﴾ (Al-Anbiyāʾ 21:20)
فَتْرَةٌfatrah (noun (ism dhāt)): an interval, a period of slackness. ﴿عَلٰى فَتْرَةٍ مِّنَ الرُّسُلِ﴾ (Al-Māʾidah 5:19)
Form II (tafʿīl) فَتَّرَ يُفَتِّرُ تَفْتِيْرًاfattara yufattiru taftīran: to give respite, to slacken, to lighten. ﴿لَا يُفَتَّرُ عَنْهُمْ وَهُمْ فِيْهِ مُبْلِسُوْنَ﴾ (Az-Zukhruf 43:75)