Definition of "grok"

I do not grok all fullness of what I read. In the history written by Master William Shakespeare I found myself full of happiness at the death of Romeo. Then I read on and learned that he had discorporated too soon – or so I thought I grokked. Why?

1961, Robert A. Heinlein, Stranger in a Strange Land, New York: Avon, page 106

Grok―and then it's clear, without anybody having to say it.

1968, Tom Wolfe, The Electric Kool-Aid Acid Test

He freely plucks notions and verbiage from science fiction to describe everything from mountain-related undertakings to political subterfuge – like "grok", a term from Robert Heinlein's Stranger in a Strange Land, to denote intuitive understanding.]

[2008 December, Leslie Anthony, “Running from Babylon”, in Skiing, volume 61, number 4, page 116

Because what he never managed to grok then was that the company he created was destined to become a template for all of humanity, the digital reflection of masses of people across the globe. Including — and especially — the bad ones.

2018 August 2, Kara Swisher, “The Expensive Education of Mark Zuckerberg and Silicon Valley”, in New York Times‎

Today we take a few moments to help you grok some of the ways that victims of TU can up their hipness – if we may use that term without being considered old school.

2008 August, Stanley Bing, “New Help for Hodads”, in Fortune, volume 158, number 3, page 152