Seguin (səgēnˈ) [key], city (1990 pop. 18,853), seat of Guadalupe co., S central Tex., on the Guadalupe River; inc. 1853. Among its many industrial products are textiles, construction materials, plastic products, steel, and processed foods. The city was founded (1831) by members of the Texas Rangers and named after Col. Juan Seguin, a hero of the Texas Revolution. The river and nearby Lake McQueeney attract vacationers. Texas Lutheran Univ. is there.