Douglas Harper's Etymology Dictionary
Latin, literally "in the place of a parent" (see parent).
Wiktionary
adv. (context legal English) Assuming the place or position of a parent
WordNet
adv. in place of the parents; "we had to punish this child in loco parentis"
Wikipedia
The term in loco parentis, Latin for "in the place of a parent" refers to the legal responsibility of a person or organization to take on some of the functions and responsibilities of a parent. Originally derived from English common law, it is applied in two separate areas of the law.
First, it allows institutions such as colleges and schools to act in the best interests of the students as they see fit, although not allowing what would be considered violations of the students' civil liberties.
Second, this doctrine can provide a non-biological parent to be given the legal rights and responsibilities of a biological parent if they have held themselves out as the parent.
The in loco parentis doctrine is distinct from the doctrine of parens patriae, the psychological parent doctrine, and adoption. In the United States, the parental liberty doctrine imposes constraints upon the operation of the in loco parentis doctrine.
Usage examples of "in loco parentis".
I did it because she was my guest and I temporarily stood in loco parentis to her.
Shes a judge, and shed just start babbling about in loco parentis like Mr.
McBee knew that she served in loco parentis, and while she was not quite power mad with that authority, she took it seriously.