ر ص صr-ṣ-ṣ
(ن) رَصَصَ يَرْصُصُraṣaṣa yarṣuṣu (original form) ⟵ رَصَّ يَرُصُّ رَصًّاraṣṣa yaruṣṣu raṣṣan: to join bricks or parts together and set them firmly, to cement with lead.
مَرْصُوْصmarṣūṣ (passive participle, ism mafʿūl): cemented with lead, joined part to part and made firm. Only once in the Quran, in a simile for ranks drawn up in battle: ﴿كَاَنَّهُمْ بُنْيَانٌ مَّرْصُوْصٌ﴾ (Aṣ-Ṣaff 61:4)