Declension table of ?regivas

Masculine	Singular	Dual	Plural
Nominative	regivān	regivāṃsau	regivāṃsaḥ
Vocative	regivan	regivāṃsau	regivāṃsaḥ
Accusative	regivāṃsam	regivāṃsau	reguṣaḥ
Instrumental	reguṣā	regivadbhyām	regivadbhiḥ
Dative	reguṣe	regivadbhyām	regivadbhyaḥ
Ablative	reguṣaḥ	regivadbhyām	regivadbhyaḥ
Genitive	reguṣaḥ	reguṣoḥ	reguṣām
Locative	reguṣi	reguṣoḥ	regivatsu

Compound regivat -

Adverb -regivas