The affix kvip comes after the verb bhū 'to be' when the word so formed denotes a name or surety.,
As, विभूः 'a person called Vibhu'; प्रतिभूः 'a surety i. e. he who stands intermediate between the debtor and the creditor'.,
भुवः सञ्ज्ञा-अन्तरयोः
Adhyāya 3 · Pāda 2 · Rule 179