Jef ‧ fer ‧ son, Thomas /ˈdʒefəs ə n $ -fər-/ BrE AmE
(1743–1826) the third President of the US, from 1801 to 1809. Jefferson was an important member of the Continental Congress and wrote most of the Declaration of Independence. When he was president, the US bought the Louisiana Purchase, and the SLAVE TRADE officially stopped being legal.