I found a bio of a professor and it has a sentence as below
Not totally satisfied with the extend and nature of understanding of biological phenomena I could reach via pure experimental approaches, I moved on and turned to ...
I'm not sure what the 'extend' here means, which is a noun. I checked in the Webster dictionary and it does not have a noun form of this word.
For your reference, here is the bio. I hope I don't infringe privacy putting the link here.