The same here. This macOS (mine is Big Sur version 11.1) functionality still doesn't work in the Evernote environment. What is a pity because it forces us to leave the application, enter another one (Dictionary), do the word search and return to Evernote... Will they ever solve this (big) issue?
My Evernote version is 10.5.0 build 2114 beta
Editor: v113.0.14585
Service: v1.24.2