Up On Meaning

Example :   The tour guide was certainly up on his history.2001 June 24, Christopher John Farley, "The New Video Wizards," Time:  Says Sigismondi: "I don't watch [MTV]. I'm really not up on what's trendy."2011 Aug. 25, William Grimes, "Casey Ribicoff, Senator’s Widow and a Style Leader, Dies at 88," New York Times (retrieved 3 Jan 2012):  â€œShe was up on everything,” said the biographer A. Scott Berg. “Not just the news but every play or film or book.”