The Collaborative International Dictionary of English v.0.48:

Bon \Bon\, a. [F., fr. L. bonus.]
   Good; valid as security for something.
   [1913 Webster]

The Free On-line Dictionary of Computing (30 December 2018):

bon

    (From "Bonnie", Ken Thompson's wife) A language
   designed by Ken Thompson and later revised by him to produce
   B.

   [When?  Features?]

   (1997-02-04)