ر ک مr-k-m
(ن) رَكَمَ يَرْكُمُ رَكْمًاrakama yarkumu rakman: to pile one thing upon another layer upon layer, to heap up. ﴿وَيَجْعَلَ الْخَبِيْثَ بَعْضَهُۥ عَلٰى بَعْضٍ فَيَرْكُمَهُۥ جَمِيْعًا﴾ (Al-Anfāl 8:37)
رُكَامٌrukām (on the pattern of فُعَالٌfuʿāl): that which is piled one upon another, a layered heap. ﴿ثُمَّ يَجْعَلُهُۥ رُكَامًا﴾ (An-Nūr 24:43)
مَرْكُوْمٌmarkūm (passive participle, ism mafʿūl): heaped up in layers. ﴿سَحَابٌ مَّرْكُوْمٌ﴾ (Aṭ-Ṭūr 52:44)