Thomas Jefferson could at least read in 5 or more languages:
http://wiki.monticello.org/mediawiki/index.php/Languages_Jefferson_Spoke_or_Read
Jefferson said in an April 12, 1817 letter to Joseph Delaplaine, "I was educated at William and Mary college in Williamsburg. I read Greek, Latin, French, Italian, Spanish, and English of course, with something of it’s radix the Anglo-Saxon." In addition to the languages he lists, there is some evidence that Jefferson was attempting German.[3]
Jefferson had dictionaries, vocabularies, and grammars in a number of other languages in his library. These included Arabic, Gaelic, and Welsh, amongst others. However, without confirmation from Jefferson himself, the most we can assume is that he was "dabbling" in these languages, and never achieved a notable degree of fluency.