Net Book Agreement n (Journalism & Publishing) a former agreement between UK publishers and booksellers that until 1995 prohibited booksellers from undercutting the price of books sold in bookshops. Abbreviation: NBA Collins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014