Thread:Lukesmissinghand/@comment-22439-20170531010820/@comment-1327106-20170620044530

You realize you're arguing about whether she was legally taken in, in a fictional setting that is not based off modern day Japan? We don't know if there is a formal process in the AoT world.

And in English "adopt" means: to take by choice into a relationship; especially :  to take voluntarily (a child of other parents) as one's own child (per Merriam Webster dictionary)

Mikasa's situation fits the English definition of the word. A native Japanese speaker might attach a legal connection to it, but it doesn't matter in English, which is the language of this wiki.

This is why translation cannot be done as a one to one thing. (This is my day job.  I work in localization.)