Root ر ع ب(r E b) has 2 unique word forms and appears 5 times in the Quran.

English gloss Frighten, Terrified

Word Translation Occurrences
ٱلرُّعۡبَ the terror, [the] terror, [the] terror, the terror 6
رُعۡبٗا (with) terror, (with) terror 2
ٱلرُّعۡبَۚ [the] terror, [the] terror 2