This post comes courtesy of Yishai Lemberger, who asked me in shul yesterday, while we were saying עלינו, what does גלולים mean. I assumed it meant idols of some sort, and assumed that the word appears in תנ”ך. But I had never given the word any thought nor did I actually know what it means.
The word appears 48 times in תנ”ך (according to Even Shoshan), always in the plural. 40 of those occurrences are in the Book of Ezekiel, six in I and II Kings, and once each in Jeremiah and Deuteronomy.
It is a derogatory word for idols or foreign gods, or as HALOT puts it “always polemically and contemptuously.” Possible etymologies are “shapeless things, blocks”, jalil (Arabic), “venerated” which would explain the connexion to gods, or גלל – “droppings”, which would explain the derogatory sense “dungy things” as BDB puts it.