It is a term in jurisprudence within the conditions of the person who can lead a congregational Prayer to Aadil عادل. Aadil means a pious person who does not deliberately commit sinful acts, and if it happens that he committed a sinful act, he immediately repents and seeks forgiveness and never insists on wrong. Such pious, God fearing, obedient person is called Aadil.
(Just) is a literal linguistic translation of Aadil but it does not include the full meaning of the term Aadil.
Wassalam.