Surname (for commoners) is placename-derivative, indirectly from prominent aristocratic Leiningen family; many similar placenames in "Leiningerland" northeast of Kaiserslautern GE centered around Gruenstadt. Most Leiningers in U.S.A. appear to be descended from two ancestral groups:
1) Philipp Leininger, b. ca.1545 prob Gruenstadt area GE, relocated 1570 to Lichtenberg, Bas-Rhin, France; sons include Johann Heinrich Leininger ca. 1585; and grandsons incl. Heinrich's sons Philipp Jacob Leininger, b. 1627, and Johann Jacob Leininger, b. 1638, who both moved to Mietesheim 1679-80; other descendants in Bas-Rhin and nearby Germany; numerous desc. in U.S.A. over two centuries. Another group as yet unconnected, early 1600s in Wolfisheim, Bas-Rhin.
2) Leininger around 1550, Reutlingen, Wuerttemberg, Germany. Descendant Sebastian Leininger came to Philadelphia, Pennsylvania, in 1748 with grown/young children; killed in 1755 in Indian massacre, leaving descendants of dau. and 2 youngest sons Johannes b. 1733 and Georg b. 1737. Other presently unconnected Leininger groups southwest of Kaiserslautern GE, and along the east bank of the Rhine River in Baden-Wuerttemberg GE, each with descendants in U.S.A.