"grok" was a word used by the man who'd been raised on Mars. I'm not going back to Heinlein to find out if the word was a Martian word. It meant to comprehend far more deeply than normal use of English words (otherwise we'd use those normal words). One of the things the Martian lad wanted to understand was humor.

The book came out in the 60s. I've used the word on occasion, but not occasionally.

I thought I invented a word while dog walking (and I mean really walking a real dog) three days ago. The words was "tentativity" referring to the habit of being tentative or talking in that manner. I took credit for inventing it, but on the BBC website I saw the word: "incentivity" so I reckon probably my word is not 'my' word.

My word.