نسم نسو and نسى نش
تَنَاسَاهُ He pretended that he had forgotten it: (Ṣ, KL,* TA:) and (TA) he forgot it; (MA, KL,* TA;) like نَسِيَهُ↓: (TA:) [or] he constrained himself to dismiss it from his mind. (MA.)
تُنُوسِىَ It (a word or the like) was forgotten by degrees. (Occurring often in the larger Lexicons.)
النَّسَا [vulg. عِرْقُ النَّسَا, app. The sciatic vein;] the portion, in the thigh, of the vein (عِرْق) which, in the back, is called the وَتِين, and which extends to the shank, where it is called the صَافِن: (IAth, TA, voce أَبْهَرُ:) or the صاَفِن and عرق النسا are two branches of one عِرْق [or vein]: (Ibn-Seenà, vol. i. book iii. p. 608: [where the opening of each of these to let blood is mentioned:]) [in a solid-hoofed animal,] النسا is a vein (عِرْق) proceeding from the hip, or haunch, lying within each thigh, then passing by the hock, so as to reach the hoof: when the breast is fat, each of its thighs becomes cleft by two large portions of flesh, and the نسا runs between them, and is apparent. (Ṣ.) [In the present day it seems to be applied by some to the sciatic nerve: and عِرْقُ النَّسَا, as also النَسَا alone, often signifies sciatica, or hip-gout: see نِقْرِسٌ and also شَنِجٌ.]
مُنْسِيهَا for مَنْسِئِهَا: see a verse cited voce عُقْبَةٌ.