“Jehu.” This name likely means “He is Yahweh.” Yahweh is announcing that He will bring an end to the idolatrous house of Omri. Jehu is famously mentioned and depicted on the Black Obelisk of Shalmaneser III, called “Jehu, the son of Omri.” Assyrian kings called Israel “Omri Land” because of his dominance and dynasty. Since Jehu killed the last member in the dynasty of Omri and became king, it seems appropriate that the Assyrians would call him “the son of Omri,” even though there was no blood connection between Omri and Jehu. Jehu was Yahweh’s agent of judgment against Baalism and the dynasty of Omri-Ahab. Nevertheless, the biblical text expresses reservations about him, and one reason for that was he still followed the sin of Jeroboam, namely, the worship of the golden calves at Bethel and Dan.
“Nimshi.” The name “Nimshi”has been found on two storage-vessel potsherds at Tel Rehov in the Beth-shan valley. They have been dated to approximately the same period as the biblical Jehu. Of course there is no way to know if this is the same person as Jehu’s grandfather mentioned here in 2 Kings 9:2, but it shows that Nimshi was a known name at that time.
“an inner room.” The Hebrew is idiomatic: a room within a room.