What is Prochein Amy?

Legal Definition
More correctly prochain ami. Next friend.

2. He who, without being appointed guardian, sues in the name of an infant for the recovery of the rights of the latter, or does such other acts as are authorized by law; as, in Pennsylvania, to bind the infant apprentice. 3 Serg. & Rawle, 172; 1 Ashm. Rep. 27. For some of the rules with respect to the liability or protection of a prochein amy, see 4 Madd. 461; 2 Str. 709; 3 Madd. 468; 1 Dick. 346; 1 Atk. 570; Mosely, 47, 85; 1 Ves. Jr. 409; 10 Ves. 184; 7 Ves. 425; Edw. on Parties, 182 to 204.
-- Bouviers Law Dictionary
Legal Definition
Next friend, which see.
-- Ballentine's Law Dictionary