practice. (1) A friend of the court. One, who as a stander by, when a judge is doubtful or mistaken in a matter of law, may inform the court. Any one, as amicus curia, may make an application to the court in favor of an infant, though he be no relation. (2) Describes a person or organization who is not a party to a lawsuit but that has a strong interest in the case aligned with one of the parties and wants to educate the court on its position usually an influential, well known organization.