A judge, arbiter, one who pronounces judgment. From the root din (to judge). This word emphasizes the role of rendering verdicts and settling disputes with authority.
God is the ultimate dayyan — the Judge of all the earth. When Abraham asks 'Shall not the Judge of all the earth do right?' (Gen 18:25), he appeals to God's nature as perfectly just arbiter. Human judges were appointed to reflect God's justice (Ex 21:6; 22:8), but their authority was always derivative. The prophets condemned corrupt judges who perverted justice, and looked forward to the Messianic King who would judge with righteousness (Isa 11:3–4).