Root ر ك م(r k m) has 3 unique word forms and appears 3 times in the Quran.

English gloss Pile up, accumulate, Heap

Word Translation Occurrences
رُكَامٗا (into) a mass, (into) a mass 2
فَيَرۡكُمَهُۥ and heap them, and heap them 2
مَّرۡكُومٞ heaped up, heaped up 2