Literally: An arbitrator, referee; also, an umpire. A judge.
Allah, the supreme Arbiter. The One Who makes the final decision of the nature of all matters. The One Who prevents everything from wrongdoing or corruption or transgression.
The words Hâkim, Hakam and Hakîm both derived from the same root ح ك م , but Hakam is a verbal noun which emphasizes the delivery of justice, while Hakîm is a noun which indicates the essential nature of the possessor of hikmah, and Hâkim is a noun which indicates the essential nature of the possessor of rule and decree (Hukm).
(For further explanation please refer to the compilation Al-Hakam.)