ر ع بr-ʿ-b
(ف) رَعَبَ يَرْعَبُ رُعْبًاraʿaba yarʿabu ruʿban: to terrify; the lexicographers say the basic sense is filling up (رَعَبَ الحَوْضَraʿaba al-ḥawḍa = he filled the cistern).
رُعْبruʿb: terror that fills the heart, dread — a fear that fills the breast. Five times in the Quran, each time in this noun form: ﴿سَنُلْقِيْ فِيْ قُلُوْبِ الَّذِيْنَ كَفَرُوا الرُّعْبَ﴾ (Āl ʿImrān 3:151); ﴿وَلَمُلِئْتَ مِنْهُمْ رُعْبًا﴾ (Al-Kahf 18:18)