The Aramaic-influenced noun gav (found in the Aramaic sections of Daniel) means the back of the body, or the midst/interior of a space. In Daniel it describes the interior of the fiery furnace and similar enclosed spaces.
Though a small word, gav ('midst') in Daniel 3 carries enormous theological weight: 'Shadrach, Meshach, and Abednego fell bound into the midst of the burning fiery furnace' (Daniel 3:23). The miracle of their deliverance from the gav of the furnace, and the appearance of a fourth figure like 'a son of the gods,' prefigures the Emmanuel truth — God is present with his people even in the furnace of affliction. The New Testament echoes this in Revelation 1:13, where the Son of Man walks in the midst of the lampstands.