Van Bu·ren (vān byŏŏr'ən) The eighth President of the United States (1837-1841). A powerful Democrat from New York, he served in the U.S. Senate (1821-1828), as secretary of state (1829-1831), and as Vice President (1833-1837) under Andrew Jackson before being elected President in 1836. He unsuccessfully sought reelection in 1840 and 1848.