While "source listings as an aid to debugging" was definitely done, and still is (e.g. Microsoft Windows source is available to researchers), Wikipedia disagrees with the use of the term "open source" as ever meaning this.

The term "open source" was first proposed by a group of people in the free software movement who were critical of the political agenda and moral philosophy implied in the term "free software"

https://en.wikipedia.org/wiki/Open-source_model

Interesting. I'm probably confusing some things. I was under the impression that the term "open source" was older than both the free software movement and "open source" as defined by Eric Raymond et al. Not sure where I remember that from. Thanks for correcting me.

That's an interpretation that I had not seen before. You would probably need to provide some more references to evidence for that claim in order to combat the down voting.