A journey made by Meriwether Lewis and William Clark, during the presidency of Thomas Jefferson, to explore the American Northwest, newly purchased from France, and some territories beyond. The expedition started from St. Louis, Missouri, and moved up the Missouri River and down the Columbia River to the Pacific Ocean. The information that Lewis and Clark gathered was of great help in the settlement of the West. (See also Louisiana Purchase.)
noun 1. the northernmost island of the Hebrides, in NW Scotland. 825 sq. mi. (2135 sq. km).
noun, Chemistry. 1. any substance capable of forming a covalent bond with an acid by transferring a pair of electrons to it. noun 1. a substance capable of donating a pair of electrons to an acid to form a covalent bond Compare Lewis acid
noun, Building Trades. 1. an anchor bolt having a conical base around which concrete or lead is poured to hold it.
noun 1. a light, air-cooled, gas-operated machine gun with a circular magazine, first used in World War I. noun 1. a light air-cooled drum-fed gas-operated machine gun used chiefly in World War I