From adoptō (“to choose”) +‎ -īvus.

• (Classical Latin) IPA^(key): [a.dɔpˈtiː.wʊs]
• (modern Italianate Ecclesiastical) IPA^(key): [a.dopˈtiː.vus]

adoptīvus (feminine adoptīva, neuter adoptīvum); first/second-declension adjective

1. adoptive (by adoption)

First/second-declension adjective.

• “adoptivus”, in Charlton T. Lewis and Charles Short (1879), A Latin Dictionary, Oxford: Clarendon Press
• “adoptivus”, in Charlton T. Lewis (1891), An Elementary Latin Dictionary, New York: Harper & Brothers
• "adoptivus", in Charles du Fresne du Cange, Glossarium Mediæ et Infimæ Latinitatis (augmented edition with additions by D. P. Carpenterius, Adelungius and others, edited by Léopold Favre, 1883–1887)
• “adoptivus”, in Gaffiot, Félix (1934), Dictionnaire illustré latin-français, Hachette.