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.
This Victorian style, red sandstone building was built in 1855 and designed by architect James Renwick, Jr. It was originally the home of the first Secretary of the Smithsonian, Joseph Henry, and his family and is the oldest building on the National Mall. The Smithsonian Castle is centrally located on the National Mall and serves as good place to start a tour of the Smithsonian museums. You can view a 24-minute video on the Smithsonian and learn about other Washington, DC attractions as well.