1 Kings 9:18 - Albert Barnes' Notes on the Bible

Tadmor - The Hebrew text here has, as written, Tamor (or Tamar), and as read, Tadmor. That the latter place, or Palmyra, was meant appears, first, from the distinct statement of Chronicles 2 Chronicles 8:4 that Solomon built Tadmor, and the improbability that the fact would be omitted in Kings; secondly, from the strong likelihood that Solomon, with his wide views of commerce, would seize and fortify the Palmy-rene Oasis: and thirdly, from the unanimity of the old versions in rendering Tamar here by Tadmor. The probability seems to be that Tamar was the original name of the place, being the Hebrew word for “a palm,” from where it is generally agreed that the town derived its name. Tadmor was a corrupt or dialectic variety of the word, which was adopted at the city itself, and prevailed over the original appellation. No reference is found to Tadmor in the Assyrian inscriptions, or in any Classical writer before Pliny.