When we see a visitor with a correctly formatted &gclid= parameter, in the landing page url, then we can set this visitor as coming from adwords.
gclid should be at least 10 characters long, and less than 100.
Ideally we would also store the gclid value in the log_visit table for later use, eg. importing analytics conversions from Piwik into Adwords.
This would likely be done in a new plugin
Follows up #4261
Just got this issue this morning with a client of mine. In fact all their data are biased to analyze because they did not set the url tracking. This default configuration based on gclid would be very interesting to have. The issue is really well identified.
I'm not 100% sure but that seems something easy and valuable todo. I reckon could be done around https://github.com/matomo-org/matomo/blob/3.12.0-b7/plugins/Referrers/Columns/Base.php#L378 but we wouldn't be able to detect the word.