WordNet (r) 3.0 (2006):

grok
    v 1: get the meaning of something; "Do you comprehend the
         meaning of this letter?" [syn: grok, get the picture,
         comprehend, savvy, dig, grasp, compass,
         apprehend]

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

grok
 /grok/, /grohk/, vt.

    [common; from the novel Stranger in a Strange Land, by Robert A. Heinlein,
    where it is a Martian word meaning literally ?to drink? and metaphorically
    ?to be one with?] The emphatic form is grok in fullness.

    1. To understand. Connotes intimate and exhaustive knowledge. When you
    claim to ?grok? some knowledge or technique, you are asserting that you
    have not merely learned it in a detached instrumental way but that it has
    become part of you, part of your identity. For example, to say that you ?
    know? LISP is simply to assert that you can code in it if necessary ? but
    to say you ?grok? LISP is to claim that you have deeply entered the
    world-view and spirit of the language, with the implication that it has
    transformed your view of programming. Contrast zen, which is similar
    supernal understanding experienced as a single brief flash. See also glark
    .

    2. Used of programs, may connote merely sufficient understanding. ?Almost
    all C compilers grok the void type these days.?


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

grok

   /grok/, /grohk/ (From the novel "Stranger in a Strange Land",
   by Robert A. Heinlein, where it is a Martian word meaning
   literally "to drink" and metaphorically "to be one with")

   1. To understand, usually in a global sense.  Connotes
   intimate and exhaustive knowledge.

   Contrast zen, which is similar supernal understanding
   experienced as a single brief flash.  See also glark.

   2. Used of programs, may connote merely sufficient
   understanding.  "Almost all C compilers grok the "void" type
   these days."

   [Jargon File]

   (1995-01-31)