How to count occurrences of a word in all the files of a directory?

I’m trying to count a particular word occurrence in a whole directory. Is this possible?

Say for example there is a directory with 100 files all of whose files may have the word “aaa” in them. How would I count the number of “aaa” in all the files under that directory?

I tried something like:

 zegrep "xception" `find . -name '*auth*application*' | wc -l 

But it’s not working.