I'm not claiming that "discard" is a git action. I'm claiming a git user should understand what's meant by the phrase "discard changes". Run git status in a repo that has changes in the working directory. In the resulting output, there's a message:

Changes not staged for commit:
    (use "git add <file>..." to update what will be committed) 
    (use "git restore <file>..." to discard changes in working directory)
        ...

The phrase "discard changes" is used consistently in git's output.