ar Rahman and ar Raheem
Bismillah.
Ar-Rahman: The Entirely Merciful, Ar-Raheem: The Especially Merciful
Both of the names Rahman and Raheem come from the root Ra-ha-meem (ر ح م), these names are similar so they require a parallel explanation. What is Rahmah? Rahmah is mercy. In the dictionary it means: compassion, kindness and gentleness. Also when a person is kind, compassionate and tenderhearted towards the other. So Ar-Rahman and Ar-Raheem: The One who has a lot of Rahmah, The One who shows a lot of rahmah, He expresses a lot of Rahmah. There are two Names of Allah with the same root, to emphasize that Allah is really the MOST Merciful, there is no one else who is more merciful than Allah subhanahu wa ta’ala.