Princeton's WordNet(0.00 / 0 votes)Rate this definition: 1  deltoid, deltoid muscle, musculus deltoideus(adj) a large triangular muscle covering the shoulder joint and serving to abduct and flex and extend and rotate the arm. 2  deltoid(adj) triangular or suggesting a capital delta, with a point at the apex.
Founded in 1846, Washington, D.C.'s Smithsonian Institution is the world's largest museum and research center, with 19 museums and galleries, nine research facilities, and the National Zoological Park. Most of these attractions are located in and around the National Mall, between the Lincoln Memorial and the U.S. Capitol.
Museums Located on the National Mall. 1  Smithsonian Institution Building - 1000 Jefferson Drive SW, Washington, DC. 2  The historic building, also known as the Castle, is a good place to start your tour of the museums. 3  The Smithsonian Information Center is located here and you can find a map and schedule of events.