Every so often, I take a look at terminology preferences in our industry. A great way to get a quick macro-level feel for usage is to track Google searches for "webinar" and "webcast" using the Google Trends analytic tool. Here are my results as of January 15, 2018. I set my timespan for 5 years, so as to smooth out any temporary anomalies.
As you can see from the overall comparison graph, "webinar" continues to grow in common usage, while fewer and fewer searches look for "webcast."
The webinar line is in red and the webcast line is in blue. The sharp drops correspond to Christmas each year… a common result for business-related search terms.
The worldwide usage map shows a fascinating regional distinction:
If you want to do business in China, "webcast" is the term to use.
And finally, I did a quick listing of the top five geographies performing searches for each term:
I'm not sure what's going on with webcasts in Sri Lanka, but if you want to ponder a real head-scratcher, take a look at what happens if you shorten the timeline to look for top regions searching for these terms over the last 12 months:
Nigeria, Sri Lanka, and the tiny remote island of St. Helena?!? I invite you to add a comment with your theories and speculation as to why these locations are using these search terms more than the US or Canada. I have no idea.