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.
What is the cost of admission to the Smithsonian? You'll save some money on your next trip to Washington, D.C. Admission to 14 Smithsonian museums and the National Zoo is free. To learn more before visiting, check out the Smithsonian's visitor information, including hours, parking, and access for visitors with disabilities. The Smithsonian is a MuseumSpot Must-See Site. View more articles, exhibits, questions or trivia.