🔼The name Tartak in the Bible
The Avvites made Nibhaz and Tartak, but neither deity has been identified. In The Gentile Nations of 1864, George Smith supposes that Tartak was in fact Tarkat, "the special divinity of the first Assyrian dynasty," named Dercetades by the Greeks. Barnes' Notes on the Bible submits that Nibhaz and Tartak may be intentional corruptions of Nebo and Tir, which are known Babylonian names.
According to the Talmud (Sanh.63a), Nibhaz and Tartak were a dog and an ass.
🔼Etymology and meaning of the name Tartak
It's unclear what Tartak might mean, but Gesenius derived it from a Pahlavi phrase Tar-thak, meaning Profound Darkness or Hero Of Darkness (the Pulpit Commentary decrees that "these guesses cannot be regarded as entitled to much attention"). Alfred Jones (Dictionary of Old Testament Proper Names) believed that this deity signified the moon.