firmness, thorough understanding

, (S, A, L, &c.,) aor. , (A, Msb, JM, &c.,) inf. n. رُسُوخٌ, It (a thing, S, Msb) was, or became, firm, steady, steadfast, stable, fixed, fast, settled, or established, (S, A, L, Msb, K,) in its place. (L.) [Hence,] رَسَخَ الحِبْرُ فِى الصَّحِيفَةِ (tropical:) [The ink became fixed upon the piece of paper or the like]. (A, L.) And الرَّقُّ الدَّهِينُ لَا يُرْسَخُ فِيهِ الحِبْرُ (tropical:) [Ink will not become fixed upon oiled parchment]: (A:) or الوَرَقُ الدَّهِينُ [oiled paper]. (TA.) And رَسَخَ فِى العِلْمِ (tropical:) He became firmly rooted, or grounded, or established, in science, or knowledge. (L.) And العِلْمُ يَرْسَخُ فِى قَلْبِ الإِنْسَانِ (tropical:) Science, or knowledge, becomes firmly rooted, or grounded, or fixed, in the heart of man. (L, A. *) And رَسَخَ حُبُّهُ فِى قَلْبِهِ (tropical:) [The love of him, or it, became fixed in his heart]. (A.) ― -b2- [Hence also,] said of a pool of water left by a torrent, (tropical:) It sank into the earth, and disappeared: (JK, A, K:) inf. n. as above. (JK, TA.) And, said of rain, (tropical:) It sank into the earth so that the two moistures [meaning that of the rain and that of the soil beneath] met together. (A, K.) ― -b3- رَسْخٌ [as an inf. n.] signifies (assumed tropical:) The connexion of the soul of a human being, after its departure from the body, with an inanimate, not increasing, body: distinguished from نَسْخٌ, which is with the body of another human being: and from مَسْخٌ, which is with the body of a beast: and from فَسْخٌ, which is with a plant. (Marginal note in a copy of the KT.) But see 1 (last sentence) in art. فسخ

, (JK, K,) inf. n. إِرْسَاخٌ, (TA,) He made it firm, steady, steadfast, stable, fixed, fast, settled, or established, (JK, K,) in its place. (JK.)

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.)