a·mi·cus cu·ri·ae 
(ə-mē′kəs kyrē-ī′)
(ə-mē′kəs kyrē-ī′)n. pl. a·mi·ci curiae (ə-mē′kē)
A party that is not involved in a particular litigation but that is allowed by the court to advise it on a matter of law or policy directly affecting the litigation.
[Latin amīcus cūriae : amīcus, friend + cūriae, genitive of cūria, court.]