Literally, a friend of the court in Latin.

"Under the Roman law, the amicus, at the court's discretion, would provide information on areas of law beyond the expertise of the court. It is from this practice that the English common law concept of an amicus develops where the amicus as a disinterested bystander would, at the court's request or permission, inform the court on points of law. The first reported case where the court allowed an amicus curiae to participate in a trial solely to protect third party interests was in 1736 in the case of Coxe v Phillips 95 ER 152 (KB 1736).”, observed by the High Court of Kuala Lumpur in TSC Education Sdn Bhd v Kolej Yayasan Pelajaran Mara & Anor [2002] 5 MLJ 577.