12/07/2017 Writing goes ahead of my mind

As I was writing an article, which I decided not to post, I found myself, to my suprise,  typing an adjective "versant." I meant it to be well-versed or familiar, but just after thinking of this word, I had a strange feeling. That word isn't familiar enough to me to use it without hesitation. Nor do I remember when I came across this word. I even began to doubt whether I had ever encountered it or not. Such was the doubt that it seemed likely to me that I totally made up this adjective. But my fingers typed it without any hesitation. This lack of hesitation felt incompatible with the lack of any familiarity with it. What do you think about this phenomenon?