I know they won't let you call a plugin WordPress-xxx, but they will allow WP-xxx. What are the rules surrounding WooCommerce?
I'm posting this answer because the accepted answer is slightly misleading, as it implies that you cannot use the trademarked name at all. While not 100% wrong, it's also not 100% right.
It is correct that unless you are WooCommerce, you can't call your plugin "WooCommerce Cool Add-on". But you can call it "Cool Add-on for WooCommerce." See "Why can’t I use someone’s trademark/brand as my plugin name?"
Also, if you're submitting to the .org repo and you are concerned about making sure your naming convention is correct/acceptable/valid, just submit it the way you interpret the rules. If it's unacceptable, they will tell you and then you adjust it to be approved. OR, just get on the #PluginReview Slack channel and ask up front. @Ipstenu and @otto42 can give you a solid thumbs up/down on whether your name will pass muster.
From the Plugin Developer FAQ
For example, if you submit “WooCommerce Tango Salsa Add-on” that would make your slug
woocommerce-tango-salsa-add-onby default. If you don’t work for WooCommerce, we would just change that to
It appears that the policy is, if you don't work for WooCommerce, you aren't supposed to use "WooCommerce" in your plugin names.
I did some research on the subject. The answer is that there is no consistent policy from Automattic on this. I have been personally threatened by Automattic for using "WordPress", but not "WooCommerce". Specifically, they are not defending "WooCommerce" on their own controlled marketplace:
So it looks to me that you can call a plugin "WooCommerce" all day and they have chosen to only defend the copyright in certain cases. I'll consider this post a notice on the subject. I intend to use the term "WooCommerce" commercially, which I consider in the public domain, as the copyright is not defended. [see you in court!]. Have a nice day.