 While the film is loosely based on Philip K. Dick (qv)s "Do  Androids Dream of Electric Sheep", the title comes from a book by  Alan Nourse (qv) called "The Bladerunner".  William S. Burroughs (qv) wrote a screenplay based on the Nourse  book, and a novella entitled "Blade Runner: A Movie."  Ridley Scott (qv) bought the rights to the title but not the  screenplay or the book. The Burroughs composition defines a blade  runner as a person who sells illegal surgical instruments.