الوارث
كلمة (الوراث) في اللغة اسم فاعل من الفعل (وَرِثَ يَرِثُ)، وهو من...
An integral part of prayer that is essential for it to be valid, such as standing, bowing, prostrating, etc.
"Rukn" (pl. arkān) (pillar) is that part of something upon which its existence depends, like the "arkān" of the prayer, which are statements and actions of the prayer necessary for its validity. Deliberate abandonment of any of such "arkān" renders the prayer invalid. However, if the praying person abandons them out of forgetfulness or ignorance, then the prayer will not be valid unless he makes up for what he missed.
"Rukn": foundation, support, strongest side, pivot. Derived from "rakn", which means strength, firmness. Other meanings: the supporting pillar of something, which keeps it erect.