Green’s Dictionary of Slang

1. in popular hippie n.² (3) and mystic use, to appreciate, to understand and experience completely; usu. in phr. grok the fullness.

[1961		R.A. Heinlein Stranger in a Strange Land 17: There was so much to grok, so little to grok from].
1968		T. Wolfe Electric Kool-Aid Acid Test (1969) 147: In his movie — right right right — and they all grok over that. [Ibid.] 360: They sit in cars with special amethyst-tinted windows and grok in fullness the Pacific sun.
1971		Time 29 Mar. 61: Esalen T-groups frequently use the term grokking in their touch therapy.
2003		Eble Campus Sl. Nov. 3: grok – understand.
2015		J. Stahl OG Dad 129: At her age, I wasn’t sure she could grok the implications of global outsourcing.
2021		J. Ellroy Widespread Panic 51: Billy grokked my Landing Strip antics.

2. used as a command.

2002		J. Ellroy ‘Where I Get My Weird Shit’ in Destination: Morgue! (2004) 33: Grok the speedometer – it tops out at 150 miles per hour.
2023		(con. 1962) J. Ellroy Enchanters 15: I hooked north [...] The swank level popped exponential. Grok the deep lawns and tall hedgerows.