fosterage

When Mardas saw Gharib his reason fled, and he said to him, "O my son, I am under thy protection: so deliver me in right of my fosterage of thee!"

From The Book of the Thousand Nights and a Night — Volume 06 by Sir Richard Francis Burton

The terms of fosterage seem to vary in different islands. 

From Journey to the Western Islands of Scotland by Samuel Johnson

Connected apparently with the tribal sentiment were the strange customs of fosterage and gossipred.

From Irish History and the Irish Question by Goldwin Smith

Indeed, I repent me of what was done by me to her, for that, in any case, she is my nurse and hath over me the right of fosterage.

From The Book of the Thousand Nights and a Night — Volume 07 by Sir Richard Francis Burton

Rejoined Aslan, "O Commander of the Faithful, he is no father of mine, save by right of fosterage; my father was none other than Ala al-Din Abu al Shamat."

From The Book of the Thousand Nights and a Night — Volume 04 by Sir Richard Francis Burton