सनिंससनिवांसम्

This is derived from सनोति or सनति root. As अञ्जित्वाग्ने सनिं ससनिवांसम् ॥ The augment इट् is added, there is no change of अ of सन् to ए, nor the elision of the reduplicate before वस् ॥ The other form is संनिवांसम् when not preceded by सनिम् ॥ This form ससनिवांसम् is Vedic, in secular literature we have सैनिवांसम् ॥,