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Definitions of grok on the Web:

• get the meaning of something; "Do you comprehend the meaning of this letter?"
  wordnetweb.princeton.edu/perl/webwn

• To grok is to share the same reality or line of thinking with another physical or conceptual entity. Author Robert A. Heinlein coined the term in his best-selling 1961 book Stranger in a Strange Land. ...
  en.wikipedia.org/wiki/Grok

• Grok is an open-source web framework based on Zope 3 technology. The project was started in 2006 by a number of Zope 3 developers. Grok has since then seen regular releases. Its core technologies (Martian, grokcore.component) are also used in other Zope-based projects.
  en.wikipedia.org/wiki/Grok_(web_framework)

• To have an intuitive understanding of; to know (something) without having to think (such as knowing the number of objects in a collection without needing to count them); To fully and completely understand something in all its details and intricacies
  en.wiktionary.org/wiki/grok

• To reach total understanding of a subject. From Robert Heinlein's Stranger in a Strange Land.
  esut.edu.ng/Glossary%20G.html

• This one is, well, HUGE! Here's a whole essay attempting to grok the meaning of grok. CLICK HERE
  www.mithrilstar.org/glossary.htm