المَفْسَى

The anus [as being the place of emission of the فُسَاء]. (TA.) مَا أَقْرَبَ مَحْسَاهُ مِنْ مَفْسَاهُ [How near is his mouth to his anus!] is a prov. [expressive of wonder at a man's shortness: see مَحْسًى, in article حسو]. (S.)