(ن) رَسَا يَرْسُوْ رُسُوًّاrasā yarsū rusuwwan: to stay fixed, to become firmly settled; with this basic sense it occurs in various meanings.
رَاسِيَةٌrāsiyah pl. رٰسِيٰتrāsīt and رَوَاسِيْrawāsī (active participle, ism fāʿil): that which stands fixed or firmly set; in the Quran رَوَاسِيْrawāsī is used of mountains. ﴿وَجَعَلْنَا فِيْهَا رَوَاسِيَ﴾ (Al-Mursalāt 77:27); ﴿وَقُدُوْرٍ رّٰسِيٰتٍ﴾ (Sabaʾ 34:13)
Form IV (ifʿāl) اَرْسٰى يُرْسِيْ اِرْسَاءًarsā yursī irsāʾan: to fix in place, to set firmly, to anchor. ﴿وَالْجِبَالَ اَرْسٰهَا﴾ (An-Nāziʿāt 79:32)
مُرْسًيmursany (passive participle, ism mafʿūl; also used as a noun of time or place, ẓarf): fixed, firmly set; the place or time of anchoring or setting firm. ﴿بِسْمِ اللّٰهِ مَجْرِۦهَا وَمُرْسٰهَا﴾ (Hūd 11:41); ﴿اَيَّانَ مُرْسٰهَا﴾ (Al-Aʿrāf 7:187)