We are developing a SaaS product that can be extended by developing add-ons or plug-ins. We are calling those extensions "skills", exactly the same way Amazon's Alexa calls its extensions. Our product is completely unrelated to Alexa or Amazon, but we started using the "skills" word from the beginning and it stuck.
I've been trying to find through all the Amazon Echo and Alexa legalese but haven't been able to find anything related to using the word "skill" to represent an extension of a software product.
We are a U.S. based company. Could we get in trouble in the future because of this, or is "skill" considered a broad word that we can use without incurring in any trademark violations?
From purely logical speculation, it must be open for use.
Even Alexa Skills are always specified as just that: "Alexa Skills". Similar to how the word "App" is generic and you can specify "Amazon App", "Android App", or "iOS App". In fact, Apple even tried and failed to trademark the term "App Store". 2011 Article.
And Apple has a long list of trademarks found here.
Amazon has a trademark list as well, and is "non-exhaustive" like Apple's, to mean that there may be more. They do own:
ALEXA
ALEXA FUND
ALEXA GADGETS
ALEXA ONBOARD
ALEXA PRIZE
But the word "skill" doesn't even appear anywhere on the list, not even as "Alexa Skill" nor "Amazon Skill".
So it looks safe, but if you want a definite answer, contact a trademark lawyer to look into it. I don't think we can offer a concrete answer here. And even a trademark lawyer probably won't give you the crystal ball answer to whether Amazon will try to trademark "skill" in the future or not. But that's why I included the anecdote about Apple's attempt with "app store". Even if they try, it's probably unlikely they'll succeed.