I found the phrase in this sentence,
There are way over 10,000 numbered examples in The Cambridge Grammar, and thousands more given in passing in the text.
I couldn't parse this last part at first. Not sure if it is "to give in" (which sounds quite wrong), or "in passing" (meaning casually, sounds wrong; not part of the main subject, also sounds wrong), or "passing in", or it was "given a pass", or something else. I only know that if I omitted that in passing part, it will make more sense.
I looked up "pass in" in a few dictionaries, nothing came up.
After some twenty searches or so, I finally found this definition:
in passing: by the way; incidentally: he mentioned your visit in passing
which is helpful, since I can understand given incidentally in the text.
But I am still a bit unsure...
Do I understand that sentence correctly?