Solomon Judah Löb HaKohen Rapoport (Hebrew: ? ?; June 1, 1786 - October 15, 1867) was a Galician rabbi and Jewish scholar. He was born in Lemberg, Kingdom of Galicia and Lodomeria. He married in 1810 Franziska Freide Heller, the daughter of the well-known Aryeh Leib Heller, and was instrumental in publishing the work Avnei Miluim of his father in law. He wrote both the index, sources and numerous comments.
After various experiences in business, Rapoport became rabbi of Tarnopol (1837) and of Prague (1840). He was one of the founders of the new Wissenschaft des Judentums movement. His chief work was the first part of an (unfinished) encyclopaedia ("Erekh Millin", 1852). Equally notable were his biographies of Saadia Gaon, Nathan ben Jehiel (author of the Arukh), Hai Gaon, Eleazar Kalir, and others.
Thrown upon his own resources about 1817, Rapoport became the collector of the meat-tax on farmers. He had already given evidence of marked critical ability, though his writings previously published were of a light character--poems and translations. His critical talent, however, soon revealed itself. In 1824 he wrote an article for Bikkure ha-'Ittim on the independent Jewish tribes of Arabia and Abyssinia. Though this article gained him some recognition, a more permanent impression was made by his work on Saadia Gaon and his times (published in the same journal in 1829), the first of a series of biographical works on the medieval Jewish sages. Because of this work he received recognition in the scholarly world and gained many enthusiastic friends, especially S. D. Luzzatto.
After the fashion in rabbinic circles, Rapoport was known by an acronym "Shir", formed by the initial letters of his Hebrew name "Sh"elomo "Y"ehuda "R"apoport. Shir literally means "song" in Hebrew.
Rapoport died in Prague.
Solomon Judah Löb Rapoport notes that according to the Masoretes there are ten vowel sounds. He suggests that the passage in the Sefer Yetzirah, which discusses the manipulation of letters in the creation of the world, can be better understood if the Sephirot refer to vowel sounds. He posits that the word sephirah in this case is related to the Hebrew word sippur ("to retell"). His position is based on his belief that most Kabbalistic works written after Sefer Yetzirah (including the Zohar) are forgeries.