The Jargon File (version 4.4.7, 29 Dec 2003):

prettyprint
 /prit'ee?print/, v.

    (alt.: pretty-print)

    1. To generate ?pretty? human-readable output from a hairy internal
    representation; esp. used for the process of grinding (sense 1) program
    code, and most esp. for LISP code.

    2. To format in some particularly slick and nontrivial way.


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

prettyprint

   /prit'ee-print/ (Or "pretty-print") To generate "pretty"
   human-readable output from a hairy internal representation;
   especially used for the process of grinding program code.

   [Jargon File]

   (1995-02-15)