Cite
 
NIL: /nil/

No. Used in reply to a question, particularly one asked using the ‘-P’ convention. Most hackers assume this derives simply from LISP terminology for ‘false’ (see also T), but NIL as a negative reply was well-established among radio hams decades before the advent of LISP. The historical connection between early hackerdom and the ham radio world was strong enough that this may have been an influence.