_Wide Adoption_ means many platforms, doesn't it? If you use Groovy, you're limiting yourself to the JVM. All the other languages mentioned, i.e. Scala, Clojure, Ruby, and Python, have both JVM and CLR versions. Since Oracle's aquisition of Java 2 yrs ago and its subsequent courtroom behavior, it's important to have a scripting language that runs on both the JVM and CLR, just in case. There's no move whatever to port Groovy to the CLR.

As for wide adoption, Groovy's used in Grails but not many people seem interested in it as a standalone language. See O'Reilly's book sales for the year to March 2012 (http://radar.oreilly.com/upload/2012/03/Lang_QTR_Units_PrevY...).