Kshetraja (kṣetraja)

A kshetraja is a son born of the field, meaning a child fathered by someone other than the husband but legally belonging to the husband's line. The Mahabharata needs the category constantly, since Dhritarashtra, Pandu and Vidura are Vyasa's biological sons but Vichitravirya's heirs, and the five Pandavas are the sons of gods but the sons of Pandu. The epic uses it to argue, more than once, that fatherhood is a matter of dharma and acknowledgement rather than only of blood.