adoptional,a.|əˈdɒpʃənəl| [f.prec. + -al1. Cf.nation-al, etc.] Of or belonging to adoption. 1861W. H. Mill Pantheist. Princ. (ed. 2) 212 Leaving them [the Evangelists] to describe severally the natural and the adoptional lines of this, and withholding the descent of the only true parent.