I wouldn't agree with that. Custom would imply there's literally only one purpose for the language. Groovy has a lot of relevant applications outside of gradle

I wouldn't agree with that. Custom would imply there's literally only one purpose for the language. Groovy has a lot of relevant applications outside of gradle scripts. It's great for testing any JVM language, the basis of things like Jenkins pipelines, a generally useful extension language to embed in any JVM based software, and a myriad of other potential uses including full application development as a first class JVM language. Just because you personally wouldn't prefer to do those things doesn't change the general nature of what it is.