Below is the first ever appearance of the word 'fanzine' *anywhere*. It was coined by Louis Russell Chavenet in his DETOURS #5 (October 1940) and gradually replaced the earlier 'fanmag'.

Photos by Jim Doran, 2018.

A year later 'fanzine' had already escaped into the wild in what's the earliest use of it beyond our little sub-culture that I'm aware of (halfway down first column):

Alas, I've lost the details of who sent me this and so can't credit them.