1. \Not\ [Contr. from ne wot. See 2d {Note}.]
   Wot not; know not; knows not. [Obs.] --Chaucer.
   

2. \Not\, a.
   Shorn; shaven. [Obs.] See {Nott}.
   

3. \Not\, adv. [OE. not, noht, nought, naught, the same word as
   E. naught. See {Naught}.]
   A word used to express negation, prohibition, denial, or
   refusal.
         Not one word spake he more than was need. --Chaucer.
         Thou shalt not steal.                    --Ex. xx. 15.
         Thine eyes are upon me, and I am not.    --Job vii. 8.
         The question is, may I do it, or may I not do it? --Bp.
                                                  Sanderson.
   {Not . . . but}, or {Not but}, only. [Obs. or Colloq.]
      --Chaucer.
   

The Boolean function which is true only if its input is false. Its truth table is:

 A | NOT A
 --+----------
 F |   T
 T |   F