Adrogation, among ancient Romans, was a kind of adoption in which the person adopted was free, and consented to be adopted by another. It was done at the assembly of the people while the commonwealth subsisted, and later by a rescript of the emperors. The Roman practice of adrogation required the adrogator to be at least 60 years old, for otherwise it was expected that they be procreating rather than adopting. Exception was made for the infertile and those who wished to adopt within the family.
This is contrasted with arrogation, in which one claims another for oneself without the right.
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This article incorporates text from a publication now in the public domain: Chambers, Ephraim, ed. (1728). Cyclopædia, or an Universal Dictionary of Arts and Sciences (1st ed.). James and John Knapton, et al.