رسخ

رَاسِخٌ ذ Anything firm, steady, steadfast, stable, fixed, fast, settled, or established [ in its place (see 1)]. (S, A, Msb.) You say جَبَلٌ رَاسِخٌ A firm, or steadfast, mountain. (A.) And in like manner دِمْنَةٌ رَاسِخَةٌ [ A black, or dark, patch of compacted dung and urine of cattle sticking fast upon the ground ]. (A.) And [hence,] لَهُ قَدَمٌ رَاسِخَةٌ فِى العِلْمِ (assumed tropical:) [ He has a firm footing in science, or knowledge; or] he possesses excellence, and large acquirements, in science, or knowledge. (Msb.) الرَّاسِخُونَ فِى العِلْمِ [in the Kur iii. 5 and iv. 160] means (tropical:) Those who are firmly rooted, or established, in science, or knowledge: (S, Bd, L, Jel, TA:) or who have made a firm advance therein: (L:) or who are far advanced therein: (Khálid Ibn-Jembeh:) or those who study the Book of God: (TA:) or those who have committed [ it ] to memory, and who call to mind [ its doctrines and precepts ] one with another. (IAar.)