NPL is the abbreviation used for ‘Non patent literature.’ It is a term used in relation to patents. NPL means documents and publications that are cited as references for being relevant in a patent prosecution. Non patent literatures are not patents or published patent applications. A magazine article or doctoral thesis relevant to a claimed invention might be cited as NPL.
NPL are documents that are not patents. They are often used when describing portions of a patent search that review web sites, technical journals and databases, and textbooks.